On the verge of turning 17, Yotsuba Mitsuru experiences his 30th break-up. Recalling the commitment he made with his best friend, who shares his birthday, a decade ago, he heads to the park to meet him. But just as he thinks he spots his friend, a sudden burst of light leaves him unconscious. Upon regaining consciousness, Yotsuba finds himself in a hospital and learns he has been bestowed with a fresh start at life... with certain conditions attached.