Fifteen-year old (east Asian age reckoning) demon prince, Myoung Seong-Joon. To become the demon lord he has attended a middleschool in the human realm and started the maturity ritual.

I’m a 2nd Year Middleschooler Becoming the Demon Lord
I’m a Chuunibyou Becoming the Demon Lord
I’m a Second Year Middle Schooler Becoming the Demon Lord
I’m Becoming the Demon Lord
I’m Currently Becoming the Demon Lord
One of them is the Devil
魔王今天中二了
마왕이 되는 중2야