On his first day at a new school, Muramachi Koharu endures stomach cramps that force him to seek refuge in the nurse's office. However, he wakes up disoriented on the landing outside the roof door, accompanied by a strange student.
Caught off guard, Koharu tries to make sense of the situation and questions the identity of the unfamiliar student. The senior student admits to being a year above Koharu and advances towards him, pushes him down, and kisses him without warning.
From there, a romantic comedy unfolds as Koharu, a transfer student who finds it hard to say no due to his kind nature, embarks on a journey with Oosugi, a faithful but foolish senpai.
