|Manga Debut||A Loser's Honor|
Uai was in the eighth grade with Yozora Mikazuki. One day, she noticed Yozora reading a shōnen manga and stated that she wasn't aware she enjoyed such things. Yozora decided she'd make it clear to Uai that the two of them are very different people so she'd inch away from her. Uai says that she's thoroughly surprised that Yozora is into those things. She excitedly exclaims that she also loves that stuff. The two began hanging out often after school and on the weekends after that. One day, Uai asks Yozora for her email address and notices that she still uses the default one. She then creates the eternalfriendship2 email address for her.
Sometime later, Yozora became the subject of bullying at school, with Uai serving as her mental support. Yozora tried to deal with the bullying on her own, not wanting to involve Uai anymore. Upon attempting this, Yozora discovers that Uai was really behind it all. Wanting to retaliate and knowing that Uai was afraid of the supernatural, Yozora took on the 'Yamiko' persona (a ghost who kills those who betray their friends) and harassed Uai. Ultimately, Uai comes to apologize to Yozora, saying that the reason for her actions was because her crush held romantic interest in Yozora.
Uai has long, shoulder-length, dark-colored hair. She has a beauty mark under her right eye and lets her bangs hang just above her eyebrows. She also had at least a single braid.
Yozora describes Uai as being a sophisticated individual who she had trouble dealing with. She was kind, a good listener, a good conversationalist and had lots of friends. Uai shared many tastes with Yozora, like enjoying shōnen manga and anime. Uai also holds a fear toward the supernatural, something Yozora uses to later get back at her. Uai later stopped being real friends with Yozora due to her love interest having a crush on Yozora. During this time, Uai went as far as to pretend to be Yozora's friend and "supported" her through bullying of which she mastermined.
- Uai's email address name is eternalfriendship1.
- It's noted in volume 16 that Uai and Yozora's story was the source for the Yamiko/Eiko story Yozora told the Neighbor's Club at the Kashiwazaki's Summer Home.