Kiamei

"Because we understand each other, I know what her decisions would be, and it's the same way around, and none of this is going to be changed by how far we're apart or how different our positions are."

- Mei to the 10th Herrscher about her and Kiana

Kiamei is the femslash ship between Mei Raiden and Kiana Kaslana from the Honkai Impact 3rd fandom.

Canon
Mei and Kiana are both teenage students who are training to become Valkyries together at St. Freya High School. They're part of the main trio in the game along with another younger girl named Bronya Zaychik. Kiana is very open towards her attraction to Mei and insists that she loves her back. A lot of the time she will blatantly flirt with Mei and carry on with perverted comments or actions to do with her, even in serious situations. Mei usually doesn't mind Kiana's actions as long as she's able to contain her public displays of affection. But after their separation since the Battle of Schicksal, it was clear that Mei became more aware of her feelings for Kiana and even stated multiple times how much she missed all of Kiana's public displays of affection, and was baffled when the Kiana she met in Arc City was not the Kiana she met in St. Freya anymore.

Nagazora Eruption 2014
They first met in the year 2014 when a Honkai outbreak took place in Nagazora and turned many into zombies. As one of the survivors, Kiana made her way to her school's rooftop for safety where she met a senior student named Mei Raiden. She turned out to be a Herrscher, but her human conscience appealed to Kiana so they fought as she tried to save her. Once Mei gained control of herself again, she tried to jump off but Kiana grabbed her hand and pulled her back up with a smile, resulting in the Herrscher deciding to hide away in Mei's heart because she could tell her host cared about this girl. From there on the two became close friends as they tried to escape their school together. Later on, Mei thanks Kiana greatly for saving her life, which is also when Kiana calls her cute for the first time.

The two later met Bronya and the three attempted to escape the ruined city. Later, Kiana was gravely injured by a Honkai beast which reawakened the 3rd Herrscher in Mei. Under the influence of the 3rd Herrscher and cradling Kiana’s unconscious body, Mei destroyed the Honkai beast that injured Kiana. This caught the attention of Himeko Murata, a Schicksal Valkyrie. Himeko and Mei fought and during the fight; Kiana suddenly woke up and destroyed Mei's Herrscher wings, bringing Mei back to her senses. The two were then taken to St. Freya High where they train to become Valkyries with Himeko as their teacher and Theresa Apocalypse as their principal.

AE Invasion
After the events of the Xuanyuan Chronicles, Himeko was hospitalized and Kiana felt extremely guilty for it. Theresa Apocalypse decided to take Kiana with her for training since Kiana didn't want to mess anything up again. While the two were training, Anti-Entropy sent a Welt Joyce clone to capture Mei and what ensued left Class Monitor Fu Hua gravely injured and Bronya & Mei unconscious. While unconscious, the 3rd Herrscher within Mei awakened and attempted to kill the Welt Joyce clone, yet was quickly overpowered due to a heart-bomb placed within her. Upon hearing that Mei was in danger, Kiana attempted to leave and help her. The two of them work together to defeat the Welt Joyce clone which leads to Mei powering up Kiana's battlesuit and their dorms being destroyed.

St. Freya
In 2016, Bronya, Kiana, and Mei were tasked to recover a battleship called the Selene. During the events of Chapter 1, Kiana saved Mei from a Honkai zombie about to attack her and the 3rd Herrscher within Mei saved Kiana from a horde of Honkai beasts. The trio soon returned to St. Freya to take the yearly Valkyrie Examination exam where during one of Kiana's nightmares Sirin calls Mei Kiana's girlfriend (though this was later changed due to censorship).

Sometime later, the trio is sent to New Zealand to recover the Gem of Desire, which has been placed inside an ex-Valkyrie named Wendy. Wendy soon lost control and became the 4th Herrscher. The three are forced to fight her and during this situation, Anti-Entropy suddenly appeared and ambushed them with a brain chip placed within Bronya. Both Mei & Wendy were captured by Anti-Entropy and a rescue mission is setup where Kiana attempted to save Mei. During the rescue attempt, Bronya sacrificed herself and fell into a coma to save Mei.

Battle of Schicksal
Things turn for the worst as Otto Apocalypse abducted Kiana and reawakened the 2nd Herrscher (or Herrscher of the Void) within her. To save Kiana, the Far East Branch of Schicksal teamed up with Anti-Entropy to defeat Otto. When Mei suddenly reunites with Kiana during the Battle of Schicksal, the 2nd Herrscher defeated Mei and takes the Herrscher core within Mei for herself. The removal of the core caused Mei to fall into a coma for some time.

The Battle ultimately ends with Fu Hua getting shot in the head by Otto, Himeko dying in an attempt to bring Kiana back, Kiana going MIA, and the rest of the group including Mei becoming fugitives.

Arc City
After a timeskip of four months, the current group consisting of Theresa, Bronya, and Mei head to Arc City after hearing about some sightings of Kiana within Arc. The three find the Ningyo, a cyborg who might have some information on Kiana’s whereabouts. However, Rita Rosseweisse, a powerful Schicksal Valkyrie ambushed them and resetted the Ningyo before anything could be found.

The team later split with Theresa and Bronya heading to the Deep while Dr. Telsa and Mei went to repair the Ningyo. The Ningyo suddenly rebooted and Rita reveals Kiana’s location. However, Kiana was kidnapped by the World Serpent, a mysterious organization with suspicious motives. Rita contacts Mei for support and goes back to Arc City. The two reunite and Mei asks Kiana to return to the Hyperion. Kiana, however, could not go back. It turns out that the World Serpent has been planning to cause a Honkai eruption in Arc City to move towards their goal of enacting Project Stigma.

To save Arc City, Kiana sent the Honkai reactor flying into the sky and absorbed the Honkai energy with in the bomb. Kiana passed out and fell from the sky. Mei rushed to save Kiana only to be stopped by Durandal, the most powerful Valkyrie in Schicksal. Durandal brought Kiana back to Schicksal, and Mei was left helpless.

Thunders Over Nagazora
While imprisoned at Schicksal, a World Serpent ambush occur and Kiana used this opportunity to escape and make it to Nagazora. After detecting Kiana's energy fluctuation, Dr. Tesla also took Mei to Nagazora to reunite with Kiana once again. Mei also reunites with Raven and the two team up to find Kiana, yet it turned out that Raven wanted to kill Kiana all along. The two fight, though without her Herrscher powers, Mei couldn’t do anything. Regardless, Mei tried to stop Raven and started concentrating Honkai energy in her body. She defeated Raven and went to find Kiana. This time, however, it would not be the same.

Due to all the Honkai energy within Kiana’s body, she only had at least 2 months to live. This news devastated Mei and she found herself unable to do anything about it. The leader of World Serpent, Kevin Kaslana notices this and makes a deal with Mei: World Serpent could save Kiana if Mei becomes a Herrscher again and join them. Desperate to do anything to save Kiana, Mei gladly took the offer.

Kiana fought Mei in a desperate attempt to have her stay, yet in her weakened and dying state, she couldn’t do anything. Mei won the fight and the two parted ways once again.

Set Tomorrow Ablaze
This story arc is the time where both Kiana and Mei are in their separate organizations (Anti-Entropy and World Serpent, respectively) trying to end the disaster in their own ways. Both get sucked into the Theater of Domination where the Herrscher of Domination and its 1000 puppets reside, and the both of them try to get out/end the disaster in their own ways. As the puppets separate Mei from the theater (by creating an illusionary space) to prevent her from finding out their true goal (which is to awaken Herrscher of the Void and make Kiana and Herrscher of the Void fight for absolute control of K-423's body), Mei fights with countless puppets just to get out of the illusion and back to the theater to be able to assist Kiana as Mei is aware of her presence yet at the time Kiana wasn't. As it dawned on Mei that her fully awakened herrscher power (called Conquest) is stronger than that of Domination (meaning they can't steal hers like they did with Fu Hua and Bronya's power), she used this opportunity to be able to weaken the puppets by a lot when she slashed them down with multiple thunders accompanying it. The effects of Mei's attack caused thunders to strike down all over the Legion Theater and it startled Kiana as she was staying in the fragmented space created by the Gem of Haste along with Himeko, and at this time Himeko tells Kiana to leave and defeat the Herrscher of Dominance, and when Kiana got out, Bronya and Fu Hua inform her of Mei's assistance from somewhere in the Theater of Domination.

Kiana acknowledges this as she moves forward to fight against the Herrscher of Domination with her friends, and is grateful as she knows that Mei is there to fight by her side albeit being separated by the fragmented illusions of the theater.

As of now, it is unclear whether or not Mei saw the transformation of Kiana into the Herrscher of Flamescion in the Legion Theater.

Fanon
Kiamei is the most popular ship in the fandom and the most well known outside the fandom. Some players even state that if miHoYo does not add Kiamei into the 4th game, they should at the very least let them reunite, or give a bittersweet ending and state that if the two would get a bad ending they would quit the game. Some people might dislike the ship because they see it as "overrated" or think that Kiana is annoying and clingy. Some may even go as far as describing some of Kiana's actions towards Mei as harassment. Though as the story continues and the characters keep growing, there's still many chances for more people to come and like it, especially as their characters develop more (i.g. Kiana maturing, and Mei being more aware of who she's really fighting for).

It is the most written about ship on AO3 with FuKi (Fu Hua x Kiana) and Bronseele (Bronya x Seele) coming in second and third. This is the most trending ship in the Honkai Community with FuKiMei (a fanon ship consisting of Fu Hua, Kiana, and Mei) and BronSeele as 2nd and 3rd.

Fandom
FAN FICTION

Quotes
"I always believe in Mei. We're the best of partners, after all."

- Kiana's Herrscher of Flamescion battlesuit bridge lines

"The night is so quiet... I miss her."

- one of Mei's bridge voicelines about Kiana in the Herrscher of Thunder battlesuit

"I like how you, at the end of every mission, would kick down the dorm door, and shout "Mei, I'm home!", and then leap beside me and yell about how hungry you are... I would always rub your hair and tell you... "Welcome back!" I like all these about you."

- Mei, Chapter 8 about Kiana

"I don't need to go back to the past. Neither does she."

- Mei, Chapter 25

"If rescuing you is a sin, I'll gladly become a sinner."

- Mei, Lament of the Fallen Animated Short

"Sorry, my lady. I've kept you waiting. Have no fear! Kiana the young knight is here!"

- Kiana, AE Invasion Chapter 13

"You said you were alone. I used to be alone myself. Two ex-loners make the perfect team."

- Kiana, Chapter 16 flashback to when they first met

Trivia

 * They're both Herrschers; Mei is the Herrscher of Thunder and Kiana is the Herrscher of the Void and Flamescion.
 * Kiana loves food and Mei is an excellent cook.
 * In the game, there is a stigmata named "True Love Forever", which has art of Kiana in a tuxedo holding Mei who is in a bride outfit.
 * Kiana is often compared to a tuna as a joke by fans and developers of the game. Because of the joke, MiHoYo added in-game weapon which can be equipped on Mei named "One Salty Tuna".
 * In a manga which was later decanonized, there was a scene where Mei was worrying about Kiana and had a dream where they got happily married, only to result in Kiana dying before her eyes.
 * The trial character of White Comet (W.C.) for Chapter 17, (Thunders Over Nagazora) in the stage where Kiana and Mei fought before Lament of the Fallen (name of the animated short), W.C's stigmas are shown to have Mei stigmatas, namely; Mei: Princess (T), Mei: Bride (M), Mei: Birthday (B). See gallery for the picture.
 * In Gun Girlz/Honkai Gakuen 2 (the predecessor to HI3rd), at the end of the main story God Kiana asks if God exists and that if God does exist, let her and Mei meet again before the world resets.
 * In the Xuanyuan Chronicles, Kiana mentions having a cat named Sora. Mei believed Sora to be another girl and Bronya comments on how she "detects jealousy" which lead to Kiana having to clarify that Sora was her cat.
 * In A Post-Honkai Odyssey, an open-world game mode set eight years after the main story; says that 99% of Honkai energy is sealed on the moon, Mei's introduction states that "she is anticipating a reunion with someone special", clearly referring to Kiana. As Kiana was said to be "MIA" and it was hinted that she sealed herself on the moon along with 99% of Honkai Energy and Mei was noticed to be always looking at the moon as the APHO main character's dialogues regarding Mei said.
 * The canonicity of this game mode is however up for debate since miHoYo flips back and forth between "canon" and " non-canon" often, stating the lines "APHO is in the same worldline". So it is muddled as of now whether it is canon to the main story or not.
 * In the 2017 White Day (March 14) there were official tokens added in-game wherein two rings were seen. Namely, "cat's claw ring" which is a ring given by Mei to Kiana, and "bow ring" which is given by Kiana to Mei. The selling price for the cat's claw ring is 520, while the bow ring 1314 in-game currency. In Chinese, 520 = I love you, 1314 = forever (forever). See gallery for the picture.
 * While not exactly confirmed, it's heavily implied and commonly accepted in the community that Kiana is a lesbian.