A mysterious infectious disease forces the closure of student dormitories, leaving high schooler Kanata Yoshino stranded with nowhere to live. Late one night in a deserted park, he encounters Haruka Hoshikawa, the most popular and beautiful girl in his class, frantically waving her smartphone in the air. She claims to be hopeless with technology and unable to connect to the internet for the school's newly implemented remote classes. Yoshino agrees to help her, and she invites him back to her house. Once there, however, Haruka reveals a hidden agenda: she offers him a room in exchange for ongoing tech support. With no other options, Yoshino accepts, and the two classmates begin a secret cohabitation under the cover of lockdown. As they share daily life, Haruka's deliberately flirtatious and persuasive personality steadily pushes Yoshino's composure to its limits. Their private arrangement is further complicated when Haruka's younger sister Mayu arrives at the house unannounced. The story follows the increasingly intimate and playful dynamic between the two as they navigate remote schoolwork, family intrusions, and the growing tension of their close quarters. The manga adapts the light novel series by Senya Mihagi and spans four volumes, following the couple from their initial arrangement through the deepening of their relationship.