My First Serious Gal

Junichi is eating lunch with Yukana in the courtyard, but Ranko is with them ruining the atmosphere. Kashii Yui, a serious, prim and proper type of girl, tries to talk to him. After school, she takes Junichi to a cafe, and is interested whether Junichi and Yukana are truly dating. Junichi tells Yui just how happy he is with Yukana, but...