Villain no Gakkou

Joichiro Kirinji (15), the son of the current Prime Minister, works hard on his studies, hoping to become the "prime minister,” the most powerful man in Japan. Until one day, when he meets the “Leader of the Miran-gumi,” the man who actually controls true power in the country. Galvanized by that humiliating experience, he enrolls in Miran High School, with the goal to become the greatest man in Japan.

(Source: Kurage Bunch, translated)