Koori no Hime wa Chiisana Hidamari de Tokasaretai

Miharu Aoba is a high school boy who, in lieu of his busy parents, looks after his kindergarten-age siblings. Although he doesn't have time for romance, he enjoys spending time with his younger siblings. One day, Aoba brings them to a play date at the home of a classmate of his, the cool beauty Yuki Mizudori, who is known as the "Ice Princess." Mizudori asks him, "Can you make me smile?" A youthful romantic comedy about high school students who cherish their little siblings!

(Source: Houbunsha, translated)