SayoHina

SayoHina is the family ship between Sayo Hikawa and Hina Hikawa from the BanG Dream! fandom.

Canon
Hina and Sayo are twin sisters; Sayo is the elder, while Hina is the younger. Hina is a genius who can do things at first try, but easily gets bored while Sayo is a hardworker who often spends a lot of time mastering her skills and needs more time to learn. Sayo is serious, stiff and stoic, while in contrast Hina is very bubbly, carefree and optimistic; however due to her genius nature she has trouble understanding peoples' struggles. Both are members of their schools' student councils: Hina is Haneoka Girls' Academy's student council president, while Sayo also doubles as a discipline committee member in Hanasakigawa Girls' Academy.

Ever since the two were young, Hina had always bested Sayo in everything due to her genius nature, from simple things to test scores. As a result Sayo formed a severe inferiority complex towards Hina, and as they got older, Sayo's feeling of inadequacy caused her to drift away from her twin, until eventually she began trying to shut her out of her life entirely.

In Roselia's First Band Story, which tells the story of how Roselia was formed, Hina and Sayo's strained relationship is shown in detail. Sayo dislikes the burden of being Hina's older sister and getting constantly compared to her. She even started playing guitar only because it was something Hina wasn't doing, and because she wanted to beat Hina at something for once. This is also her biggest motive for joining and creating Roselia together with the band's vocalist Yukina.

Their first scene together is shown when Hina invites Sayo to come and watch a TV show about dogs with her and their father, where Sayo reveals Hina doesn't even like dogs, but the latter just wants to spend time with Sayo. This leads to Sayo getting angry, saying how just because they were born on the same day doesn't mean they need to do everything together, and how they promised to not get in each other's hair once they started high school. This leads to Hina apologizing and leaving Sayo's room.

In Chapter 10 of the Band Story, Hina talks to Lisa asking whether she'd really joined a band with Sayo, and then reveals that Sayo never reveals anything about herself. She then proceeds to ask whether Sayo has fun and looks happy while practicing. When Sayo finds out that Hina has joined Pastel*Palettes as their guitarist in Chapter 11, she becomes enraged and ends up blowing off at Roselia due to Ako praising her older sister Tomoe. In Chapter 13, she almost passes out due to playing too hard at home, which leads to Hina entering her room, and Sayo telling her to leave angrily. In Chapter 17, after Roselia broke up due to Yukina hiding her true intention for creating Roselia, Hina finds Sayo practicing in her room and asks whether she's going to quit. She then goes to comment how Sayo's playing sounds more individual and not as robotic as it used, which leads to Sayo telling her to leave but in a softer tone. In the final Chapter of their Band Story, one of Hina's fan approaches Sayo while they're in a family restaurant, asking whether she's related Hina. She answers "yes" and after the girls leave, thinks how she'll most likely never be able to escape Hina's shadow.

Their first major event together (outside of their respective band stories) in the game is "Wish Upon a Tanzaku". Hina wants to invite Sayo to the Tanabata Festival, but the latter is not warming up to the idea as she dislikes big crowds and festivals. Hina then goes to the festival all by herself, and while writing her tanzaku, she ends up running to Sayo who was running an errand for their parents. The two stand around awkwardly before a bird steals Hina's tanzaku and they start chasing after it. They arrive at a park which the two used to frequently go to when they were younger, and find Hina's tanzaku from the ground while reminiscing old times. Sayo also learns that Hina is part of Haneoka's Astronomy Club, which is also called the "Weirdos Club". After a while the twins return downtown where they spend time together, and Sayo writes a tanzaku as well wishing "they could be open and honest with each other", while thinking it'll eventually happen. Hina also reveals that her wish on her tanzaku was "having a fun day together with Sis".

The second, and most popular event between them, is the "Umbrella For The Autumn Rain" event which begins with Sayo seeing Hina perform on TV, leading to her compare their sounds and wonder if hers is lifeless and dull, despite being a precise player. This leads to Sayo falling into a slump, performing badly during Roselia's practices, comparing herself to the other band members and eventually refusing to play the guitar. After talking with Yukina, she realizes she needs to face Hina head-first and talk to her about her complex. During their confrontation Hina gets mad at Sayo saying she'll quit the guitar, and how Sayo is the reason why Hina started playing guitar in the first place; how she doesn't care if Sayo ends up hating her more, as long as she keeps playing. This causes Sayo snap out of her state and tell Hina how she wishes to be able to walk by her side one day and feel pride in the sound she makes. The event's main song Determination Symphony's lyrics also talks about their relationship.

Their third event together is "Twin Star Ensemble", in which Hina finds out that her Astronomy Club is going to be disbanded unless she provides tangible proof her club is doing its activities properly. She asks Sayo for help, and despite reprimanding her, decides to help Hina out with planning a stargazing event. Sayo goes and lends out astronomical books from Hanasakigawa's student library and tries reading the club's journals in order to understand what Hina finds so fascinating about them. Hina later shares a story to Lisa, Kokoro and Tsugumi how Sayo has always been a serious and sweet older sister to the point where Hina made her cry thinking about a reason for why animals could talk in a book they were reading together. Their stargazing event ends up being successful and Sayo says that it's fine they don't think the same way about everything and how everyone should be brilliant in their own way, similarly to the Gemini constallation.

In the "We're All Here! New Year's Party!!" event, in which all 25 girls assemble at CiRCLE for the New Year's party, Hina signed her and Sayo up for the party's talent contest without the latter knowledge, though she accepts the challenge. In their part they pull off two tablecloths off the table without breaking anything, where Hina also reveals they used to do it often when they were younger. After they successfully pull the trick off, Kasumi and Aya comment how in sync they are.

In BanG Dream! 2nd Season, Hina confronts Sayo and Rinko Shirokane, Sayo's fellow bandmate and their school's student council president, about holding a joint cultural festival. In the 9th episode, "School Festival Symphony", where the girls perform in order to buy time for Poppin'Party's cultural festival performance, Hina offers Sayo her guitar which she uses to play Determination Symphony with.

Hina is also very affectionate and often says she loves Sayo, which tends to embarrass and make the latter blush. Hina has also expressed envy for her bandmate Aya for attending the same school as Sayo (as the twins go to different schools).

Fanon
Sayohina has a very mixed reception in the fandom.

In the Japanese and Asian side of the fandom, it is the most popular ship, has the most fanart and fanfictions and even had a doujin event (which was held on March 21, 2019) solely dedicated to the ship. Most of the fanart is romantic in nature. Though some people shipped them before any major events, the ship's popularity raised through the roof with the Umbrella For The Autumn Rain event.

In the western side of the fandom, people who support it romantically are in the minority, and while there are people who support it platonically, the ship itself is heavily disliked and controversial due to their blood relation. In fact many people have even gone as far sent death threats to people who ship SayoHina romantically and ignored its prevalence in the Japanese side of the fandom. The ship is also disliked by many people who either ship Ayahina and Sayotsugu or both.

Fandom
Hina/Sayo tag on AO3 Sayo/Hina tag on AO3 Hina & Sayo tag on AO3

Trivia

 * Sayo is 161 cm tall, while Hina is 156 cm.
 * The girls' names are parallel to each other; the "Yo" in Sayo's name means "Night", while the "Hi" in Hina's name means "Day".
 * Hina and Sayo's voice actresses, Ari Ozawa and Haruka Kudou, have also shown support for the ship multiple times. Haruka even quote-tweeted a tweet talking about the anime's second season's beginning with one of the Japanese tags for the ship.
 * In BanG Dream! Girls Band Party!☆PICO Episode 24, which is titled "Twin Rhythm", it is shown that the two share some kind of telepathic connection.
 * Hina is the only person Sayo refers to with her first name and without honorifics.