Koichi is a 20 years old smart student who has no luck with woman. When he's not studying, he spends his free time locked at home without interaction with the outside world. Until one day he receives a strange mail. A huge package with a little girl named Yuna hiding inside. Yuna is part of an experiment executed by Dr. Yoshito. She is a 8 years old little girl who likes to play and have fun until she swallows a pill invented by Dr. Yoshito and she turns into a grown up woman changing her personality by all means. Koichi, then, will have the great opportunity to study and understand the mind of a kid and a woman at the same time. Follow Koichi and Yuna journey exploring human mind and relationships. Will Koichi be able to take care properly of Yuna? Will they end up loving each other romantically? Discover all of that in this meaningful story.