High second-year student Usami Totoko has just begun living alone after her parents were transferred overseas for work. She dreams of becoming self-sufficient enough to adopt a dog, but her life skills are virtually nonexistent. Totoko survives on instant food and convenience store meals, a habit that catches the attention of a blunt but attractive clerk at her local convenience store. When he pointedly remarks that eating nothing but convenience store food is dangerous, Totoko attempts to cook for herself and accidentally triggers her apartment's fire alarm. The same clerk comes to her aid, and she learns that his apartment has just been destroyed by a fire. Feeling responsible and wanting to repay him, Totoko offers to let the young man, Inui Zen, stay at her place. Inui moves in under the arrangement that he will handle the cooking and housework in exchange for lodging, and the two begin a secret cohabitation. Despite Inui's initially cool and sharp-tongued demeanor, he proves to be a skilled homemaker who gradually reveals a caring side. Totoko, who nicknames him Inui-kun, finds herself growing increasingly conscious of his presence at home and at school, where she discovers they attend the same high school. As their daily life together unfolds, Totoko begins recognizing her feelings as romantic, while Inui's own guarded past and growing attachment to her slowly surface. The story follows the development of their relationship through the challenges of their secret living arrangement, school events, and the deepening emotional bond between a girl determined to stand on her own and a boy who, like a stray dog she has taken in, quietly learns to trust and be cared for.