Oneesan-ha no Ore ga Naze Chicchai Kimi wo Suki ni Natta noka?

During the spring break after middle school, Sukai Toochika rescues a tiny girl getting crushed on a crowded train. He assumes she's just an elementary schooler, until he enters high school and finds her in his classroom?! Standing only 140 centimeters tall and fueled by energy drinks, she may be tiny, but she's an absolute beauty.

Her name is Chito Naruse. Sukai considers himself an inveterate lover of tall, older women, so a tiny cutie like Chito shouldn't pose much of a romantic target. However, Chito kicks off a fierce assault with a bold declaration: "I'm gonna take that fetish of yours and turn it completely upside down!"

A rom-com tug-of-war over tastes between a guy who loves older women and a tiny girl begins!

(Source: Kadokawa, translated)