A nerdy high school boy named Asahi lives quietly with his older sister, but his routine is turned upside down by the frequent visits of her best friend, Hinako, whom he calls Hi-chan. As a typical otaku, Asahi is completely unprepared for Hinako, a fashionable gal with a perfect face, an openly affectionate personality, and almost no sense of personal space. She constantly flusters and confuses him by getting physically close, acting in a suggestively teasing manner, and treating him either like her own little brother or, at times, like a pet.

Asahi finds himself caught between his growing attraction to her and his inability to handle her relentless and intimate approach. While he struggles to maintain his composure, Hinako seems to take great pleasure in his awkward reactions, creating a series of lighthearted and wholesome but often embarrassing situations in his own home. The story explores the blissfully simple yet complicated dynamic of two contrasting personalities: a reserved boy who acts like a worried parent and a carefree girl whose friendliness constantly misleads his heart.

The manga, written and illustrated by Takase Waka as a serialized work, is a seinen romance that focuses heavily on character interaction rather than an expansive plot. Key characters include Asahi Igarashi, the flustered male lead; his older sister Tsukko; and the source of his confusion, Hinako Kakei. The narrative unfolds predominantly through episodic chapters that revolve around the same core premise of Hinako invading Asahi’s space and the resulting romantic comedy, which often finds its high point in major close-up panels of Hinako’s charming expressions. The series has reached a significant readership with multiple collected volumes, crossing over three hundred thousand copies in print.