Miki Ichinose is a 14-year-old schoolgirl who is very outgoing and cheerful. She lives with her parents and younger brother. She is in a romantic relationship with Satoshi Kirino who is 15 years old. They keep their relationship a secret from their parents because Miki is young and Satoshi is expected to excel in school and get into a university so he can take over the family business by his overbearing mother. One night, after a date, they sneak into a treehouse and consummate their relationship. Soon after, Miki suspects that she is pregnant and steals a pregnancy test, which her mother later finds. She is taken to a doctor who confirms her pregnancy. Initially upset, Miki's parents promise they will support her. Miki tells Satoshi of the pregnancy and he takes the news well. However, his mother is furious when she learns of it and forbids the two from seeing each other.