I (Yuko Takeuchi) is a mystery novel writer. I receive a letter from Kubo (Ai Hashimoto), a reader of her novel and a university student. Her letter states that she hears odd sounds from the room where she lives now. I becomes interested by the letter and they being to investigate. I and Kubo learn of people that lived in the apartment and their experiences including a suicide and murder.
On July 27th, university student Aoi Hinata (Miwa) has an accident. When she wakes up, Aoi Hinata finds herself in a classroom from one week before the accident. At that time, her childhood friend Riku Hasegawa (Kentaro Sakaguchi) tells her “I will tell you a secret. I can turn back time.” Aoi Hinata and Riku Hasegawa like each other, but never expressed their feelings. They share their feelings for each other and go back to one year earlier. They spend their time happily as girlfriend and boyfriend, but there is a big secret behind the time slip. In addition, July 27 is approaching.