Ever since rescuing her from nearly being hit by a car when they were kids, Tetsu Harisugawa has been on friendly terms with the beautiful Mao Satomi. Harisugawa has feelings for Satomi but does not want to confess to her due to the fear of losing their current friendship.

However, everything starts to change when one afternoon, Satomi passes by a thrift store and ends up buying a strange mirror. She stumbles upon Harisugawa afterward, only to find herself face-to-face with an oncoming car once again. Harisugawa, like in the past, swoops in to save her. But this time, he ends up trapped inside a dark, endless realm within the mirror Satomi bought.

In this sudden twist of fate, Harisugawa and Satomi work together to uncover ways to undo the mirror's curse. Little do they know, their friendly relationship will be subjected to misunderstandings that might hinder Harisugawa's chances at freedom—especially since Harisugawa himself is unaware of how Satomi truly feels about him.