Seiichi Hiratani, sometimes referred to only by his surname, is an unpopular and socially isolated student at his academy, perceived as unattractive. He has black hair, black eyes, and a skinny frame, and wears the standard academy uniform.

He becomes infatuated with Nami Kozono, the student council president, and waits outside the ladies' bathroom to hand her a note asking her out. Kozono cruelly rejects him, stating she has no interest in men and would never date him regardless.

Seeking help, he approaches Hiroko Takashiro and her witchcraft club, who use a love spell from a black magic book. They slip a magical charm into Kozono's bag while she is distracted. The next day, the spell takes effect, and Kozono becomes intensely infatuated with him. She initiates a public relationship that surprises their peers, and they become physically intimate, including a sexual encounter in the student council room that marks his first experience.

He later decides to temporarily abstain from sex to "save up," causing Kozono to believe he no longer wants her. She goes to the witchcraft club for help, but they break the love spell instead. Freed from its influence, Kozono is disgusted by their relationship and lures him to an empty warehouse. There, a group of thugs she hired assaults him. She instructs them not to kill him, leaving his fate ambiguous but suggesting possible survival.

His personality is shy, bleak, and socially awkward, especially around women. After the enchantment succeeds, he eagerly explores his sexual fantasies with Kozono and stops masturbating to focus his attention on her.

A piece of trivia notes that his full name is not stated in the anime, with some sources suggesting it may be Seiji Hiraya, though this is unconfirmed. His name was also misspelled in the English credits of the anime episodes.