Yako/Synopsis

The Misaki Stairs Arc
Yako is first seen on the other line of the phone requesting Hanako, Kou, and Nene to find her body parts, while mentioning what she used it for. Later, she runs over to the makeshift human with the body parts that the three put in a shrine-like box, which moved a bit before it falling down into the deepest part of the boundary. Frustrated at another failed attempt rebuilding Misaki, Yako then start fighting Kou which gets him turned into a doll. When sent by Hanako down to the deepest part of the boundary, Nene found and read from a book she wrote, telling her story. An entry saying how she scared a student that day, followed by a comment in red ink by someone, correcting her behavior and scolding her. Every day, Misaki came by the shrine and taught her various subjects.One day, while making dolls waiting for him to come back, she heard that her crush, Misaki, was rumored to have died on the stairs. Yako back then didn't understand death until she was older. She almost kills Nene after seeing her read the book but, with interference from Hanako, stopped it. Nene ripped her yorishiro, a pair of scissors. It showed a flashback, where Misaki was finishing cutting her hair. She retreated into the Inari statue before Misaki pulled her in to join the photo. Soon after being defeated by Hanako, she is formerly introduced to Nene in her fox form. Nene apologizes for destroying her favorite thing, petting her and calling her Fox-san, which greatly irritated Yako, in retaliatation, she bites Nene for calling her Fox-san. She threatens to bite her hand off if she calls that again and tells her to call her Yako.

The Three Clock Keeper Arc
After the events that happened during her former arc, Nene began spreading the rumors that any couple who climbs the entire length of the Misaki Stairs while holding hands and professing their love will be bound forever but you musn't touch the fourth step, or your love will be severed for all enternity; Yako finds her to file a complaint. For ever since the rumor started "every single frickin' day" couples comes to her stairs to make out with each other. After Nene said that "[her] staircase has been reborned as a sacred place for lovers" to which angered Yako, she transforms into her fox form and bites Nene on the head, remarking that the act of couples coming to her stairs to make out is abnoxious, so she has came here to get her revenge by chomping Nene. Yako then informs the latter that she saw Hanako-kun going into the science prep room a while ago. She joins Nene by sitting on head and shoulders while she going to "No. 5's place" to find Hanako. She then found Akane's hanitaro and left before Nene went to rooftop.

The Hell of Mirrors Arc
After meeting at Tsuchigomori's office, No.5 made a remark, saying that since No.2's boundary has lost it's overseer, it's probably a mess, while calling her echinococcus, to which Yako responds by calling him emo spider. She refuses to help Kou and Hanako, but is threatened into agreeing after Hanako repeatedly threatens to make Kitsune Udon out of her. She then showed Hanako and Kou a portal to No. 3's boundary using hers. Kou then began to talked about when her rumour was changed by Yugi Tsukasa and how she went crazy, and asking what that felt like. She answered that it was "definitely [her]" and that "just because [she] went beserk doesn't means [she] became someone else" while comforting Kou by saying "even if he didn't understood it, it reached him probably". But when Kou called her "Fox" on accident, she immediately bit into his head and told him to call her Nee-San instead.

Summer Light Arc
Since, Hanako can't go to the summer festival because he is an earth-bound spirit and that he can't go outside, they asked Yako to take them to a supernatural beings festival inside the school instead. Before they went, she helped dressing Nene up in a yukata and tags along. She makes a few comments through out the arc and is seen playing with a water yo-yo.