Riko Konohina has a very peculiar taste when it comes to romance—but it’s something she’s kept buried deep, refusing to acknowledge it even to herself. One day, while studying at her classmate Tomoka’s house, a young girl with a backpack suddenly appears in front of them. To Riko’s shock, Tomoka has a much younger elementary school-aged little sister! The moment she lays eyes on the unbelievably cute girl, time seems to stop for Riko. But there’s a catch—Tomoka’s little sister doesn’t seem to like her one bit… Thus begins a heart-thumping, chaotic, age-gap girls’ love comedy between a high school girl who loves kids and a grade schooler who hates being treated like one!