My Youth Romantic Comedy Is Wrong, As I Expected @ comic, Vol. 17 (manga) — Wataru Watari

Planning for the Soubu High prom continues, and Yukino is steadfast about working without Hachiman and Yui. But when she receives complaints from parents worried about moral impropriety, it might just put the kibosh on everything. Even worse-the parents' representative is Yukino's mother, whose disarming social grace makes negotiating all but futile! Can Hachiman help without going back on his word to Yukino? And as he spends more time with Yui, where will his feelings take him?