Tsubarika

Tsubarika is the femslash ship between Tsubaki Aoyagi and Rika Seto from the D4DJ fandom.

Canon
Rika and Tsubaki are childhood friends as well as the main vocalists of their respective DJ units, Merm4id and RONDO. In addition to this, they attend the same university together with the other Merm4id and RONDO members. The two were classmates and friends in elementary and middle school, but got separated in high school. Their first major interactions happened in D4DJ: Groovy Mix's third event story, which also revolves around Rika trying to reconcile with Tsubaki during their hot springs trip.

Sun, Fun, Moon & Steam!
Throughout the event, Tsubaki claims she doesn't want to talk to Rika and does her best to avoid the latter, even going as far as running into the sauna.

D4 FES. -Happy Moment-
In the event, the girls are paired up into 6 different mixed groups, with one of them consisting of Tsubaki, Rika, Miyu and Aoi. The moment Rika steps into the hotel room and sees Tsubaki, she jumps in to hug her, much to Tsubaki's embarrassment.

♯Party ♯Resort ♯Survival
In Tsubaki's Episode, titled "The Time That Fate Linked Us Together", the two sit around the bonfire and Rika comments how beautiful Tsubaki looks as the light of the fire reflects on her. Tsubaki tells her to leave her alone but drops it when Rika says Tsubaki already knows she can't do that. Rika surprises Tsubaki by shouting and mentioning how them sitting around a bonfire brings her back memories about their fifth grade camping trip, where they camped in the mountains, cooked together at a campsite, and also went through a test of courage. Tsubaki says she accidentally fell into the mud, started crying and then Rika held her hand while helping her walk and comforting her. Rika asks if that really happened, and Tsubaki sighs saying of course Rika wouldn't remember, how Tsubaki was nothing but dead weight while Rika pulled her along, but Rika says it's highly unlikely that she saw the situation that way. Tsubaki tells Rika she's grateful for what she's done for her all the way from the past to the current time and how she'll have to return the favor someday, before ordering Rika to forget everything she just said. Rika declines and swears she'll never forget because they are close friends. Rika then expresses her surprise over them reuniting and how it feels like a miracle, leading Tsubaki claiming they are just "hopelessly tied together", but Rika assures the term fits them well.

Fanon
Although not as popular as Tsubaoi, Tsubarika has a fair amount of supporters. Fans of the ship especially enjoy their status as childhood friends, as well as the way Rika enjoys teasing and being close to Tsubaki, and how the latter in turn usually gets embarrassed or denies the things Rika says.

Since crush of Tsubaki on Aoi is already more or less confirmed and it is not canonically explained whether she loves her just because of androgyny or not, fans of this ship love to speculate that she might also develop some feelings for Rika as well.

Fandom
FAN FICTION

Trivia

 * The two were featured together in D4DJ: Groovy Mix's app icon at one point.
 * In one of their live interactions, Rika enthusiastically shouts they'll get things done with the power of friendship. In another, she calls Tsubaki with the nickname "Tsu-chan", who then gets flustered and mumbles how she needs to do her best to concentrate.