RuiKasa

"Only you would be bold enough to bring up wanting to try doing something no one's ever done before, Tsukasa-kun. And that's why you're so wonderful!"

- Rui in "Mascot Greeting" first side story

RuiKasa is the slash ship between Rui Kamishiro and Tsukasa Tenma from the Project SEKAI fandom.

Canon
Rui and Tsukasa are third year high school students and members of the theater troupe Wonderlands x Showtime. They are a "well-known duo of weirdos" at their school due to the fact they cause ruckus around the campus daily, which, most of the time, is due to Rui's experiments. As stated in the "The Climax! Kamiyama Cheer Squad!" event, the rest of the student body refers to them as the "oddball one-two," or just the "one-two" for short.

In the current canon, Rui sees Tsukasa not only as a troupemate, but as a close friend he is immensely grateful to. Tsukasa was the first to place unconditional trust in Rui's "crazy" directions and follow them through with all he has, and he's also the reason Rui was able to branch out socially and at school. Tsukasa is noted to be the catalyst of Rui's change by Rui himself during "A Once-In-A-Lifetime Pandemonium?!."

Similarly, Rui also filled a long-empty gap for Tsukasa. He was the first with a director's ability to become so invested in Tsukasa's journey as an actor, and Tsukasa fully trusts in all of the directions and advice Rui gives him, no matter what other people think of them. Additionally, despite all of his complaints about Rui's conduct, he enjoys spending time together with Rui at school, and, during their second year wherein they were in different classes, the two would still often seek each other out outside of class.

Main Story
Tsukasa and Rui first meet during their unit's Main Story. Tsukasa is looking for people to join the newly formed troupe, and he's impressed by the freelance solo performance Rui does at Phoenix Wonderland, before he runs away from the guards for performing without permission. He eventually tracks Rui down to their school's roof, where Rui had been waiting while he watched Tsukasa search the school for him via his drones. After a brief conversation about being each other's fans, Tsukasa asks Rui if he wants to join his troupe, which Rui initially denies but later agrees to after Tsukasa assures him that he will perform any role Rui gives him to "12,000% satisfaction."

The troupe is then fully formed after Rui also invites Nene to join. Throughout the story, it is brought up time and time again that they are a dynamic duo when it comes to performance. Tsukasa is always being pushed to his limits by his director because, according to Rui, "he is an actor worthy of the stage" and can always go the extra mile.

However, on the night of the troupe's first proper performance, the robot Nene uses fails onstage during a scene she's doing with Tsukasa. Rui hurriedly ends the show, and Tsukasa later shouts at Nene, blaming her for ruining the show and expressing frustration over the fact that the audience couldn't experience the performance he wanted to show them. Rui, as Nene's close friend and the one who brought her into the troupe, harshly criticizes Tsukasa for shouting at her for something she couldn't help. He comes to the conclusion that Tsukasa is shallow and doesn't truly care about shows as he, Nene and Emu do, only using them as a vehicle for his own narcissism, and leaves the troupe.

Even after Tsukasa is able to rediscover his true reasoning for loving shows and reconciles with Nene, Rui refuses to return. However, Tsukasa doesn't give up, insisting Rui is an important part of the troupe, and puts on a show for Rui together with Emu and Nene in his SEKAI—the world of his heart—in order to convey their likemindedness, apologize for forgetting something so important, and ask Rui to return. Rui, as someone who never thought anyone would be likeminded and has never had such a grand gesture extended to him, is moved by this, and finally agrees to rejoin.

In the Wonderlands x Showtime Digest (a shorter, animated summary of the unit's Main Story), this scene is fleshed out, adding extra shots of Tsukasa kneeling to Rui at the edge of the stage as they're both lit up by spotlights, and extending his hand for Rui to take.

It's On! Wonder Halloween!
In the "It's On! Wonder Halloween!" event, Tsukasa is injured by one of Rui's robots while rehearsing. Despite the injury not being severe and Tsukasa insisting he's totally fine, Rui is deeply shaken by this, beginning to subconsciously fear abandonment by Tsukasa. As a result, Rui starts to hold back, making his initially "crazy" directions far more tame, which confuses the rest of the troupe.

Tsukasa is the one to voice this confusion as the two later get into an argument over it, frustratedly shouting at Rui for not giving him his usual style of direction, but Rui angrily denies any change. The two leave to cool off, and Tsukasa explains to Emu that the reason he was so frustrated was because he "killed the director's confidence," and that Rui isn't really the one he's angry at at all.

Rui, with the help of Nene and KAITO, is able to recognize that his issue stemmed from fear that the injury would cause Tsukasa to leave, just as the children he used to attempt to direct as a child did whenever he suggested something too dangerous. He's able to reconcile with Tsukasa the day after, both of them apologizing and coming to understand the issues the other was facing.

The event highlights the mutual trust, concern and respect they both have for one another through the lens of Rui trusting Tsukasa to perform excellent feats, being concerned for his wellbeing despite this, and respecting his wishes to continue, as well as Tsukasa trusting Rui with directing the show, being concerned for his mental wellbeing despite this, and respecting his personal boundaries. It is brought up again in "Revival my dream": while Tsukasa does believe Rui's directions are crazy, he also fully trusts that they're safe.

Kamiyama High Festival!
While rehearsing the proposal part of Romeo and Juliet for their play, Rui volunteers to be Tsukasa's partner. Tsukasa plays the part of Romeo, saying "O Juliet! Sun of my life! I beg you, allow me to have your hand in marriage!!" and Rui plays Juliet, responding "Romeo... Then refuse your name and I shall swear my love!". This scene can be seen in KAITO's Secret Guidance card art, with Tsukasa extending a hand up to Rui while down on one knee.

In the same card's side story, Rui says that a lot has changed for him since Tsukasa invited him to join Wonderlands x Showtime, and KAITO remarks to himself that Tsukasa has been a positive influence on him.

Revival my dream
In the second side story of Tsukasa's "An Officer's Crisis" card, Tsukasa remembers what happened during the Halloween show and starts to worry that Rui will hold back again in their current performance, as it also involves a risky stunt that had almost injured Emu earlier in the story. This leads to him staring at Rui out of concern as the group take a break from their rehearsal until Rui notices and asks him if there's something wrong. Nene eventually points out why he's worried, and Rui reassures him that he's okay this time, saying it's all thanks to Tsukasa for going all out with his directions back during the initial issue.

During Rui's flashback, Rui's mother comforts him after he confesses he feels ostracized by the other children at his elementary school because they see him as weird. She tells him that she and his father were both also seen as weird when they met, and she believes someday he, too, will meet someone like that who accepts him as they accepted each other. This is most likely in reference to how Rui found acceptance in Wonderlands x Showtime, but it's commonly interpreted as specific to Rui's relationship with Tsukasa, as not only were they both seen as weird by others even before they met, they later went on to became notorious at their school as the "oddball one-two."

On the Stage of Dazzling Light
During the event, Rui worries about not being a good director for Tsukasa as he feels he held him back by not giving him enough different roles in their shows, and he spends most of the event looking for ways to help Tsukasa with their upcoming performance. His 4* card story also showcases this, as much of chapter 1 is him talking about Tsukasa and asking Miku if she can help him out. The two of them also have a duet section in the event's song, "88☆彡," as well as extra illustrations in the song's 2DMV.

The Gentleman Thief's Thrilling White Day?!
During the After Event Virtual Live, Rui mentions wanting "to make a chocolate statue of Tsukasa-kun and then having the real Tsukasa appear from inside of it". When Tsukasa asks how he'd do this, Rui whispers something to him, and Tsukasa then reacts humorously asking how that'd even be possible. The two are so busy whispering to each other that Len has to close the live on their behalf.

A Sorrowful Farewell at the Curtain Call
At the end of the event, the two are sat together on the train. Rui has been worrying over his future and the future of the troupe throughout the other chapters, so he has a comforting—if abstract—conversation about his worries with Tsukasa. After the two are done talking, Tsukasa says he's getting sleepy, and Rui promises to wake him once they're back. Once Tsukasa falls asleep, Rui laughs to himself about how energetic his snoring sounds. Additionally, because Emu was sleeping on Nene's shoulder in this scene, it's popularly believed Tsukasa was sleeping on Rui's shoulder as well.

A Once-In-A-Lifetime Pandemonium?!
This is the main event that showcases the effect Tsukasa has had on Rui since the two of them first met. It opens with the two eating lunch together on the rooftop and Rui dreading their upcoming school trip to Kyoto because of his past school trip experiences, but Tsukasa just encourages him to put himself out there and meet friends.

Rui is invited to room with three boys from his class who've wanted to approach him for a while, and, thinking to the advice Tsukasa gave him, agrees, becoming fast friends with them during the trip's first day. That evening, at the inn, Tsukasa is sent to their room on behalf of a teacher to check how Rui's behaving, telling Rui that they wanted him to "check on (his) partner."

Later that night, Rui and his new friends invite Tsukasa to play cards, but Tsukasa loses 5 times and is made to do a punishment game—buying drinks for the other four—which Rui says he'll do with him, and the group ends up in a pillow fight. This is expanded on in Tsukasa's "The Victory is Decided!" card's second side story, wherein the two are forced to hide in their futons (or, in Tsukasa's case, under a table) alongside Rui's friends when a teacher comes around to check if they're sleeping, and, when they then go to buy the drinks, get ambushed by the same teacher, who had suspected Rui wasn't actually asleep and didn't seem surprised that Tsukasa was with him. Additionally, since Tsukasa complains the space under the table is too small to hide under, it's popularly thought that he hid in Rui's futon with him.

The next day, Rui and Tsukasa split off from their respective groups to see the show and parade Tsukasa had invited Rui to ahead of time. Coincidentally the two run into Shizuku and her friends, who are also on a school trip, and they decide to go around together. At one point, Tsukasa gets embarrassed because of Shizuku complimenting him, and, while he's still blushing, Rui smugly comments that "oh my, so Tsukasa also gets embarrassed sometimes when he's praised."

While passing the parade, Shizuku and Rui get separated from the rest of the group with no way of contacting them, and Rui directs Shizuku in an impromptu parade performance in an attempt to catch the others' attention and let them know where they are. Upon seeing their show, Tsukasa lets out a soft laugh and makes a comment about how amazing his troupe's director is.

Later, back at the inn, Rui and Tsukasa are made to write apology letters for their disruption the night before. While they're sat alone together, Rui thanks Tsukasa for being the catalyst for his change and the reason he was able to have so much fun on the trip. Tsukasa responds that he can't take responsibility for doing so, as it was Rui who gave himself the chance to change by taking all those opportunities. Rui then invites Tsukasa to watch the sunrise by the Kamo River (a real-world famous couples' spot in Kyoto) the next morning, and, while watching Tsukasa get scolded for not writing his letter, thinks to himself that Tsukasa brings endless smiles to his face.

Other Content
In Tsukasa's 2021 birthday lines, it is stated that Rui made him a celebratory cannon filled with confetti, the dialogue being: "Tsukasa-kun, look! All of the confetti flew up so high. Now, if they manage to spread out beautifully, this will be a huge success!" and "Ooh! The celebratory cannon made by Rui is amazing! It looks like as the whole school is covered in a flurry of confetti!" This is also confirmed by Nene and Emu, who both mention the huge cannon in their own lines.

In Rui's 2022 birthday card lines, Mizuki remarks that they've noticed Rui's changed a lot for the better since they knew him, and wonders if it's because of Tsukasa's influence. Tsukasa also tells Rui not to hold back with shows or even in private, and to tell everyone if there's anything he wants to do with them.

In the Wonderlands x Showtime's 1st Connect Live "STORIES", Rui and Tsukasa perform new choreo for their first duet, KING, throughout the entirety of which they're physically close or following each other's movements.

Fanon
RuiKasa is widely considered to be the most well-known and most shipped slash ship in the fandom. The ship is supported mainly due to the pair's natural chemistry, and also the fact that they're both very popular characters. It is the most written ship on AO3 with over 2000 works; even managing to get into the Top 100 ships in AO3 of 2022. They are also the ship with most works on Pixiv as well. It's mainly rivalled by Ruinene and Emukasa, as well as Ruiemu and Nenekasa, but it's also common for all five ships to be shipped within Polyshow. RuiKasa also has slash ship rivals as well, with some also shipping all four of the game's male characters together as the poly ship Fantasista Squad. RuiKasa is often shipped alongside Emunene.

Tsukasa and Rui are often perceived as a sun and moon duo, with Tsukasa being the sun and Rui being the moon. This is due to Tsukasa and his cards being lighter and brighter in color scheme while Rui and his cards are darker in color scheme. People have also pointed out that the moon appears in Rui's fragment SEKAI while Tsukasa strives to be a star, which is what the sun is. Nene also walks away from Rui and Tsukasa in the Kami no Manimani 3DMV while she sings the line "And sleep without regard for the sun or moon."

The first RuiKasa Ship Week was held from December 25-31, 2022 under the. Prompts for the first day were "holiday, confession or hanahaki", "angst, dressing up or unit swap" for the second day, "future, AU or piano" for the third day, "first meetings, sleepover, cooking or baking" for the fourth day, "sick day, magic or personality swap" for the fifth day, "practice kiss, first date or classic plays" for the sixth day, and seventh and final day was free choice.

The second RuiKasa Ship Week was held from July 12-18, 2023 under the. The prompts were "summer festival, mythology or soulmates" for the first day, "beach, stargazing or AU" for the second day, "amusement parks, song or horror" for the third day, "bad weather, ocean or music" for the fourth day, "vacation, hospital or detective" for the fifth day, "flowers, angst or cats" for the sixth day, and seventh and final day was free choice.

The third RuiKasa Ship Week will be held from May 29-June 5, 2024.

Fandom

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 * @ruikasaweek on Twitter
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 * @daily_ruikasa on Twitter
 * @ruikasaweek on Twitter
 * @daily_ruikasa on Twitter
 * @ruikasaweek on Twitter
 * @daily_ruikasa on Twitter
 * @ruikasaweek on Twitter
 * @daily_ruikasa on Twitter

Trivia

 * Ruikasa is referred to by the "🎈🌟" and "💜💛" emojis.
 * Tsukarui, the Eastern fandom's name for the ship's swapped dynamic, is referred to by the "🌟🎈" and "💛💜" emojis.
 * Their official English kizuna titles are "Weirdo Combo", "Top☆Star?!", and "The Best Show".
 * They have a height difference of 9cm, Tsukasa being 173cm and Rui being 182cm.
 * Before the game's third anniversary, their hight difference was 8cm, Tsukasa being 172cm and Rui being 180cm.
 * Their default Cheerful Carnival Team names are "Drone Chasing" and "That's a NO For Me".
 * Tsukasa and Rui are often respectively associated with the numbers 1 and 2 both in the game and in promotional material.
 * They're known at their school as "oddball one-two," and this is also their first kizuna title in the original Japanese release of the game.
 * Tsukasa was one of the limited cards for the game's first anniversary event, and Rui was in the second.
 * After the game's third anniversary, both Tsukasa and Rui are put in Kamiyama High class 3-C. The number and letter choice may have been purposeful here, as Tsukasa = 1, Rui = 2, third year class = 3 and C (pronounced "shi" in Japanese, which can mean "four") = 4.
 * Rui's 3rd Anniversary artwork from "A Once-In-A-Lifetime Pandemonium!?" Chapter 8, is the scene where he has a pillow fight with Tsukasa, Taniyama, Miyake and Hayashi. Additionally, the artwork was posted on the 18th, 12 days before the 3rd Anniversary.
 * The OST track played during their Romeo and Juliet rehearsal in the "Kamiyama High Festival!" event is called "A True love song" and its track number is 12.
 * Their art for the summer memory photos was posted for day 12 on the 21st.
 * Additionally, Tsukasa's promotional art for the game's second anniversary was posted on day 21, however Rui's was posted on day 13 rather than 12.
 * In their unit's cover of, they are the ones to say the "one, two" lines at the beginning of the song.
 * They currently have covered 5 songs together (,, , and ), two of which being without an accompanying VIRTUAL SINGER. They also both have solo versions of Rui's second commissioned song,.
 * Nonsense Bungaku was given to them as a duet (feat. Len) during the Eve tie-in. It is about someone who was lonely but starts trusting again after they meet a certain person, which is reflective of Rui's development with regards to Tsukasa throughout the game's story.
 * In the official "KING" 2DMV, Rui and Tsukasa are represented by playing cards: Tsukasa is the king and Rui is the joker.
 * In the 3D performance of the same song during Wonderlands x Showtime's 1st Connect Live "STORIES," their choreography during the pre-chorus featured both of them reaching out to each other and Rui tilting his head backwards when Tsukasa's hand was below his jaw.
 * On September 21st, the official "Fixer" 2DMV premiered. September is the 9th month, and 21-9 = 12. Within the MV there are secret codes. These codes can roughly be translated to "Every human walks around with a different kind of suffering" and "A drowning man will clutch at a straw."
 * At the end of the music video, their bodies turn each other's respective colors, with Tsukasa's body turning purple and Rui's turning yellow. Similarly, the yellow text of the lyrics Tsukasa sings becomes dyed in purple throughout the MV.
 * Before this official 2DMV came out, "Fixer" was widely known for its unofficial 2DMV made by Suou, who illustrated the official "88☆彡" 2DMV and several of Project SEKAI's official celebratory illustrations, and Omu, one of Project SEKAI's recurring official 2DMV editors.
 * In the Sweet Magic 3DMV, Tsukasa runs over to Rui and gives him a fistbump with a wink and smile.
 * The song commissioned for Wonderlands x Showtime's Main Story,, mentions a "thick-skinned king" and an "alchemist full of desires", referring to Tsukasa and Rui respectively.
 * In Nene's initial 3* second card episode, she tells Emu that Rui and Tsukasa had to stay back at school for detention because Tsukasa almost got blown up in the school's swimming pool.
 * Their image and hair colors, yellow and purple, are complementary colors. Their secondary hair colors, orange and blue, are also complementary.
 * As of the "Connecting Painful Hope" event, Tsukasa is the character Rui has mentioned the most in his stories, at a total of 329 times. This is over 100 times more than Nene, who is second at 197.
 * In their 2022 birthday card art, Rui wears a white cravat while Tsukasa wears a yellow necktie. In their unit outfits, Tsukasa wears a white cravat while Rui wears a yellow necktie.
 * Additionally, the flower Rui is holding in his card is an aster, which means "star," and Tsukasa is associated with the stars.
 * Some fans like to believe that there is a correlation between certain lyrics in and, Tsukasa's second focus song and Rui's third focus song respectively. During the bridge of 88☆彡, the part only sung by Rui and Tsukasa, Tsukasa's line is "I wish happiness will come to that kind of you," meanwhile Rui's final solo line in DonKetsu is "I know the ending will be a happy one."
 * In 's 3DMV, Rui sings the line "Loneliness melts away with the touch of passion" while he waves to Tsukasa.
 * In Rui's 4 star card, "Appreciate That Spirit of Yours" from the On the Stage of Dazzling Light event (Tsukasa's second focus event), the book he holds has stars on it that very closely resemble those in the Nonsense Bungaku 2DMV.
 * Rui and Tsukasa's Mastery Rank 5 outfit variants from the "On the Stage of Dazzling Light" event share the same/similar colours.
 * Additionally, their "Sorrow Farewell At the Curtain Call" (Rui's third focus event) outfit variants from Mastery Rank 1 reflect each others default outfits from that event; Tsukasa's MR1 variant shares the same colours as Rui's normal "Hourglass Tuxedo" outfit, and vice versa for Tsukasa's "Advanced Tuxedo" outfit.
 * On September 4, 2023, the official Opera GX account on Twitter replied to a Twitter post about RuiKasa's "moonphases" with the caption "OPERA????", before making a reply to their first tweet saying "I will not make a definitive statement whether or not I ship Ruikasa. I shall remain ambivalent."