Sometimes a Genius's Every Action Is at the Mercy of [X].Nariyuki's mother wins a smartphone; unfortunately Nariyuki is bad at using it. Uruka finds a website suggesting studying in the bath is more effective. That night Nariyuki does study in the bath. He accidentally texts Fumino in her bath who becomes embarrassed at the thought of communicating while naked, then accidentally calls Rizu who almost drowns after imagining what it would be like to bathe together. Finally he accidentally calls Uruka in her bath that accidentally becomes a video call and they see each other naked, causing Nariyuki to drop the phone in the water, breaking it...