The Kaisei Academy (開成学園) is a preparatory private secondary school for boys located in the Arakawa ward of Tokyo, Japan. It was founded in 1871. The Kaisei Academy has since educated notable figures across many different fields and is considered one of the most prestigious schools in the country. As of 2021, the school has had the most number of entrants to the University of Tokyo, which is regarded as the best university in Japan.