Chiyomi Horikiri (Ai Iinuma) is a warm hearted high school student. She is a member of her school's basketball team. She stays bright even in a bit complicated family composition. Her boyfriend is Hiroyuki Minami (Yusei Yagi). One day, Hiroyuki Minami suddenly shrinks in size to only 15 cm. in height. He can easily fit in the palm of someone's hand. He appears in front of his girlfriend Chiyomi Horikiri.—AsianWiki

Chiyomi is a high school girl, who was born and raised in a retro Showa-era shopping district in Shonan. She is a member of the basketball club and has a kind personality that stays cheerful despite her somewhat complicated family structure. She and Minami-kun, also known as Minami Hiroyuki, a basketball star from her hometown of Shonan, have been like siblings since childhood, and they are happily in a relationship. However, one day, he suddenly becomes 15 cm in size and fits in the palm of her hand. Chiyomi begins living with him in his now tiny body.—MyDramaList