南（二宫和也饰）和千代美（深田恭子饰）是一对校园小情人，两人自交往以来，进展极为顺利，双方都为能拥有彼此而感到幸运不已。 南参加了当地的马拉松比赛，他本是被极为看好的冠军候选，由于前一晚误食有毒生蚝，比赛过程中他渐感不支，千代美察觉出南的异样而上前搀扶，却导致南被取消选手资格。 不明就里的南对千代美不由产生了抱怨，并一时激动提出分手。千代美伤心离开，却不小心摔入河中。 醒来后，千代美惊觉自己的身高竟然缩小到只有10厘米了！她找到南，两人都搞不明白为什么会发生这样的事，只好一边调查真相，一边小心翼翼地过起甜蜜的“同居生活”。Everything started when a high school couple, Chiyomi Horikiri and Susumu Minami had a mysterious and ominous fortune cookie at a Chinese restaurant:"If you stay close to him, he will become great and the two of you will be together for a long time. However, when the two of you drift apart, horrible things will happen". Just as the prophesy, on the very day when Susumu decided to leave Chiyomi, a magical curse struck Chiyomi. Believe it or not, it shrunk her into a size of merely 16 cm tall. What would happen when a tender boyfriend and a miniaturized girlfriend secretly starts living together?
