Shitsuji ga Megane wo Hazusu Yoru

Kounosuke is the son of the Sumeragi industrial group and is a playboy. Hitsuji, the head butler, always chastises him for his bad attitude. Wanting to exact revenge on his strict and handsome butler, Kounosuke slips aphrodisiac into his black tea. Even after watching him for a while, there was no change, and so to test the drug's effectiveness, Kounosuke drank it himself. As he does, the medicine takes effect immediately and causes him to become sexually excited...?!

(Source: Fusion Product, translated)