Yamagishi, Yukako

山岸由花子

Yukako is a student in love with Koichi Hirose. Initially, she was very aggressive in her affections toward him, jealously attacking those she believed were potential romantic rivals. She even went so far as to kidnap him and threaten his life if he did not return her feelings or appreciate her efforts to "change him into a better person." She had picked up false rumors that he was insufferable; these rumors were spread by Josuke and Okuyasu to help Koichi turn her away. Unfortunately for them, their measures had the opposite effect.
Later in the story, Yukako, still lovestruck, seemed to have learned from her mistake of trying to force Koichi. Unhappy about her unrequited love, she made use of the services offered by Aya Tsuji's beauty-enhancing Cinderella stand. This rendered her a bewitchingly attractive woman in Koichi's eyes, for a price and a certain time limit. During this period, she was to use a special lipstick to uphold the "magic," i.e., the stand's power.

Spoiler