Kei Kurosu, the ordinary office worker, is a being that feeds from humans' life force. Since men with strong libido have stronger life forces, usually he also sleeps with them. One day, Kei bumped into a handsome mixed-race hotel owner, Shou, who suddenly took Kei to his room and said, "I've finally found you again. It has been 20 years since the time you left our house and tell me to find you." Despite Kei having no memory about that promise at all, Shou keeps pursuing him and his body! For some reason, Kei could not use his memory modification on Shou. Moreover, he started getting addicted to Shou's taste... What actually happened in their past? Will the love born between these two different beings last forever?