How Heavy are the Dumbbells You Lift? Vol. 20

Imagawa Yoshimoto, now leader of the Space-Time Army, warns Hibiki and Ayaka that the future is in jeopardy--and it's all their fault! To save the future, they must go back in time, but what awaits them there? Meanwhile, a battle breaks out between Brazilian jiu-jitsu master Mia and...Zina?! Don't worry, everything will be all right thanks to the power of muscles!