Tsuneko serves as a hostess in a small bar. She encounters Oba Yozo when he flees police pursuit into her workplace. To shield him from a bothersome customer and the chasing officer, she declares him her "country brother" and conceals him under her skirt. After her shift concludes, she walks home alongside Yozo. Confronted again by the officer, she urges Yozo to escape and absorbs a physical assault intended for him.

This mutual disillusionment with existence bonds Tsuneko and Yozo, both confessing they feel unworthy of being human. They resolve on a double suicide, ingesting sleeping pills and submerging themselves in Kamakura's sea. Tsuneko dies in the attempt, while Yozo survives by expelling the pills. Authorities subsequently accuse Yozo of deliberately causing her death.

In other adaptations—like Usamaru Furuya's 2009 manga—Tsuneko's counterpart is named Ageha. Junji Ito's version designates her equivalent as Sachi.