Twelve year old Sei has hit puberty and is quickly becoming sexually aware, sometimes not as privately as he'd like; erections in school and other inopportune times plague him. He talks about it with his school friends, Kinta and Nyanko, in between their feuding over the affections of classmate Yumi, but can't figure out what to do about it.

Working long hours in the emergency room, nurse Kana Aoshima befriends musician and frequent hospital patient Shogo Amami. Shogo's therapy visits for his muteness and blindness happen to frequently coincide with Kana's shift, which enables the nurse to get to know the handsome artist well enough to start falling in love with him. Fate intercedes, however, when Shogo is killed after being hit by a car - a development that utterly crushes Kana's will to live. Shogo's spirit is transported to heaven, where it is given the chance to return to Earth to assist Kana through her grieving and to renew her sense of faith in the world - with the only caveat being he cannot reveal his identity to Kana.