Ten-year-old Niina Aoyagi carries the intact memories of her past life as Chitose Amamiya. Chasing a ball into the neighboring garden, she comes face to face with Atsurou Itami, now twenty-five, the man Chitose loved and the person those memories keep circling back to. Caught between a dead girl's unfinished feelings and her own growing crush, Niina sets out to keep a promise Chitose left behind.