Gentaro, Yuki, Kengo, Tomoko, Ryusei, the student council president Sugiura, the former Pyxis Zodiarts Hiroki Makise, and transfer student Erin Suda are chosen for an astronaut test in a closed environment and endurance test, but Kengo's weak constitution and the arrival of the Aquarius Zodiarts cause trouble for the group.

Yuki passes under suspicious means, while Gentaro tries to convince Erin to not follow the path the Horoscopes want of her, as well as give up her hatred for Yuki.