I Heard We're Graduating Sehaga Episode 12

A black rabbit named Black Asobin takes over Sehagaga's network and steals almost all of the girls' medals, challenging them to enter his world and get them back. After battling their way through Black Asobin's tower, Saturn, the only girl with a medal remaining, enters the world of Space Harrier and defeats Black Asobin, who is revealed to have been Center all along. For clearing the 'graduation exam', the girls gain 20 medals each, giving Dreamcast and Mega Drive more than enough medals to graduate. Saturn, being three short, is nearly forced to be held back, but Dreamcast and Mega Drive share their spare medals so she can graduate alongside them.