BokuYukie

"There he goes again. Bokuto gets depressed easily, but it's just as easy to pump him back up again." - Yukie Shirofuku from Chapter 96 BokuYukie is the het ship between Kōtarō Bokuto and Yukie Shirofuku from the  Haikyu!!  fandom.

Canon
The two of them are good friends. Yukie is aware of Bokuto's tendencies to fall victim to his mood swings like the rest of the team and knows how she can help bring him out of it if needed. Bokuto often borrows money/notes from her although he has a tendency to forget to return anything to her.

During the Spring High Preliminary Arc, Yukie confronts Akaashi and askes him if they should make sure Bokuto is in top condition by telling him a girl in the stands mentioned how cool of an ace he is.

During the Final Arc, Yukie and Kaori watch Bokuto play in the Jackals v.s. Adlers game.

Fanon
BokuYukie is not very popular as it is overshadowed by ships such as BokuAka and BoKuro. Despite it being unpopular, there are currently 29+ works of the ship on AO3.

Most fan art of the ship consists of Bokuto and Yukie eating together.

Trivia

 * They both share an interest in food.
 * Bokuto calls Yukie "Yukkipe."