Fujisaka

FujiSaka is the femslash ship between Chika Fujiwara and Ai Hayasaka from the Kaguya-Sama: Love Is War fandom.

Canon
Ai Hayasaka and Chika Fujiwara are Kaguya Shinomya's closest friends and they occasionally meet and talk to each other. At school, while in her 'gal mode', Hayasaka maintains a friendly relationship with Chika. Hayasaca (her cross-dressing butler persona) is the only 'male' character who Chika has shown genuine attraction to.

Because of the role Hayasaka plays in helping Myuki Shirogane and Kaguya Shinomya get together, she often has to eliminate factors that may potentially hinder the progress of their relationship. As such, she often clashes with Chika Fujiwara. Because of her 'chaotic' and unpredictable nature, Hayasaka sees Chika as her nemesis, even going as far as to give her the name 'Subject F'.

During winter break, Hayasaka is constantly pestered by Kaguya who talks about her kisses with Myuki in excessive detail. Eventually, she becomes frustrated and desperate to know what a kiss actually feels like. At the time, she's 'hanging out' with Chika at a mall in order to distract and prevent her from ruining Kaguya's date with Myuki. Hayasaka asks Chika how she feels about kissing and when the other girl admits she would like to be forced into a kiss by surprise, Hayasak does exactly that.

Fanon
The ship was made after chapter 152 and quickly began to gain popularity in the fandom. Though at first glance, it may seem like these two have no compatibility whatsoever, if one looked back at previous chapters, they would realize how well their characters compliment one another.

Hayasaka is reserved and stoic, while Chika is light-hearted and easy going. Hayasaka hides behind her many personalities with the intention of maintaining order. Meanwhile, Chika is always her true self and unintentionally causes chaos wherever she goes. They are Kaguya's closest friends and affect her in completely different ways - with Chika being seen as a rival, and Hayasaka - a confidant. Hayasaka has a somewhat tomboyish appearance at times, while Chika is exceedingly cute.

This ship is very new and is even less developed than the recent Ishiino pairing. Chika's and Hayasaka's moments together are few in-between and the possibility of them being a thing becomes relevant only near the latest chapters of the ongoing manga. Fans who have not read the manga and even some of the readers are not aware of the ship. There is almost no fanart or fanfictions about this ship. As such, it loses to Fujigami and Fujigane.

Fandom
FAN FICTION
 * Fujiwara Chika/Hayasaka Ai tag on AO3

WIKI
 * Ai Hayasaka's relationship with Chika Fujiwara  on Kaguya-sama Wiki