Hanako, also known as Toilet Hanako or Hanako Hasegawa, haunts a disused men's toilet at Saito High School. This scantily clad teenage ghost enjoys immense popularity in the spirit world, holding the No. 1 position for 562 consecutive weeks on the "School Spirits' Top Ten" program. Her father, Hanasaku, was a renowned school spirit in his own time.

In life, Hanako was an exemplary student celebrated for her beauty, athletic prowess, intelligence, and charisma. Her life ended tragically when she was struck by a car while fleeing bullies. Now manifesting as one of Saito High's seven school spirits, identifiable by a pink badge, she attracts the intense obsession of Kazumi Ryudo, a member of the Holy Student Council, whose fixation frequently leads to comedic or problematic scenarios.

Hanako occasionally assists the Holy Student Council in resolving supernatural disturbances. She possesses abilities like "Marshmallow Hell," used to de-brainwash Kazumi when compromised. A recurring element involves her rivalry with another female spirit, Yamiko, who forces Hanako into duels by kidnapping others—Haruto Houjo in the anime, Mutsuki Asahina and the spirit Nino in the manga—a conflict originating from a forgotten dispute over which spirit was more attractive.

Hanako's character maintains consistency across media, with no significant alterations to her core traits or backstory. She primarily functions as a supporting figure within the series' supernatural ecosystem.