Shinobu wakes up one day to an unexpected sight: a mysterious naked blonde girl lying beside him, a stranger to his memory. Clueless about her identity and the reason for her presence, he faces a perplexing dilemma. The situation escalates when his sister stumbles upon them, adding a new layer of complexity to the unfolding events. Now, Shinobu must unravel the mystery surrounding the girl in his bed while navigating the unforeseen consequences of this bizarre encounter.