My Younger Boyfriend is Occasionally So Cute it Kills Me.

Thirty-ish and gay, Shouta Kogawa has never gotten over his first love. He gets drunk out of his mind and is taken care of by the bursting-with-youth high schooler Mayu Mikuni. He comes to his senses after making an unexpected love confession to Mayu. He won't allow himself to be seduced by a straight teen... (Source: Fusion Product, translated) **Included one-shot:** Ookami Kui