Shin'yuu no Mama ja Iya Dakara.

Ai and Chiharu are classmates at the same school and best friends. However, Ai harbors feelings for Chiharu that go beyond friendship. No longer able to contain her overflowing emotions, Ai confesses her feelings to Chiharu... but Chiharu is simply bewildered. An awkward time passes between them, and a week later, Ai calls Chiharu out. "Forget about what happened that day..." However, Chiharu gives her an unexpected reply. "How about we give us a try...?" Now that they're a couple, the two secretly nurture their love so their classmates won't find out, but Ai has something on her mind...