Ushiro no Seki no Gal ni Sukarete Shimatta.: Mou Ore wa Dame kamo Shirenai. - Ch. 19

[wallsg]

Underwear as a gift is when you're sufficiently far in your relationship. Manga couples get there almost never.

He wrote the thing! Though it doesn't really follow the conversation...

Such good planning. And asking someone you're dating about helping with studying doesn't count as troubling.

He's not angry. He's just serious. If he was actually angry, I don't think he would take it out on her.

It would be an appropriate gift from Miyamura to Hori, especially if he bought something that leaned into her kink.