Original Title
白ギャルに弱みを握られた風紀委員長が、『百合トモごっこ』でグズグズにされる百合
Synopsis
Wow. All that melting sweetness — it’s coming from inside Yamami, isn’t it?
Maya Yamami (山海 茉耶) is the school’s discipline committee chair — so strait-laced and fussy that students have taken to calling her Yamami-mama. One day, she confiscates a yuri manga from Hiyori Asahina (朝日奈 ひより), a white-haired gyaru and habitual rule-breaker, and gives in to a moment of idle curiosity…
Which is how she ends up alone in the discipline room, indulging herself — and getting every second of it filmed by Hiyori, of all people.
“If the whole school saw this video, that’d be the end of the discipline committee chair, wouldn’t it? …So how about it: stick with me until Christmas Eve and play ‘Yuri Friends’?”
What choice does she have?
To protect her reputation, Maya finds herself wearing Hiyori’s perfume, shut away with her after school, subjected to relentless physical affection and kiss after kiss. But Maya, who has never been anything but serious and dutiful, finds her body and heart beginning to respond — to the unexpected tenderness Hiyori lets slip, and to the sweet, almost violent intimacy that keeps coming, day after day…
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A high school yuri about a strait-laced, secretly pent-up discipline committee chair and a white-haired gyaru.

The original Japanese Web Novel can be found on kakuyomu.
Author: しきもと ホノ (Shikimoto Hono).