Hokenshitsu no Otona na Senpai, Ore no Maede wa Sugu Dereru

Yuzuki, a senior member of the school infirmary committee, has a gentle and mature demeanor. Kyoji, a regular in the infirmary, got to know her as she teased him every day. He wanted to get back at her, so he said, "I like you..." When Yuzuki heard that, her behavior went haywire!?

(Source: Fantasia Bunko, translated)