Key Ring Lock 

Permanent part-timer Yui discovers a worn-out man fallen on the street. Unable to leave the strangely charming Toshiki alone, Yui helps him back home and then accepts Toshiki while being manipulated by him. However, when Yui gets up in the morning, he finds himself locked in and unable to leave. “Confinement is my hobby,” says a smiling Toshiki. Is this confinement, or is it … Their sensitive love flickers in the space between the normal and abnormal! (Source: Kodansha USA) Note: Includes two extra chapters.