Tsukushi and Emiri are childhood friends who have mutual feelings for each other, but when Tsukushi transfers to a new school, they are separated for a time. When they meet again after some time has passed, Emiri has a new boyfriend, her homeroom teacher, "Mio sensei." And even though Emiri is there, the teacher also makes advances on Tsukushi. When the two find out, they call the teacher in... A turbulent forbidden love story unfolds between the teacher and the two students.