Goku!! Otokojuku

Years after the events of Ultimate Path Private High School 2011, Edajima Heihachi is informed of an invading alien race called the Susanoo, who seek to harvest the testicles of Japanese men to harness the Spirit of Yamato as an energy source. As a countermeasure, Edajima assembles all Otokojuku alumni, from the now-aging fighters from Sakigake!! Otokojuku, to the still young second generation from Akatsuki!! Otokojuku, and finally to the former Ultimate Path Private High School students who transferred to Otokojuku. Led by Tsurugi Momotaro, the Otokojuku alumni embark upon a quest to outer space to protect Japan from alien invaders.

(Source: Otokojuku Wiki)