Moha has two adorable younger brothers, Masashi and Kenji, and their daily life is always filled with laughter. However, one night when their parents are away, the conversation turns to where babies come from, and Moha is shocked to discover they still believe the stork delivers babies. Realizing their lack of knowledge, she begins to feel uneasy and senses the urgent need for sex education. While playfully teasing her brothers, she gradually imparts proper knowledge, guiding them through their growth in this intimate coming-of-age story.