|This article is about a/an episode in Kamen Rider Fourze.|
|Star Follower Selection|
|Kamen Rider Fourze, Episode 37|
|Air date May 27, 2012|
|Written by Riku Sanjo|
Serious Legend Song
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.
At the JAXA, while looking for Yuki, Gentaro finds another girl named Erin Suda whom he was about became quick friends when Yuki arrives as she hints the day her dream is realized comes. However, over the former's fanatic raving over the rocket as a deity, Yuki and Erin get off on a the wrong side as the latter walks off. Soon after, Gentaro learns from a broadcast by Hayami that the school is having its annual exam to determine who can enroll in Space International Development Agency's astronaut test.
Though both would have failed, Gentaro and Yuki are saved by the bonus question thus joining Kengo, Ryusei, and Tomoko along with the other 16 that includes Erin. They are soon greeted by astronaut Chinatsu Hyuga who tells them they are to be split into groups and to spend 72 hours in an Isolation Chamber for a Productivity Test where they needed to make ten thousand paper cranes.
Tensions raise, with Ryusei failing to keep his cool, before Kengo manages to calm everyone down. But when Kengo's health problems take effect, the Aquarius Zodiarts appears from out of nowhere and uses her waters on Kengo. With Tomoko using the origami to block the cameras, Gentaro become Kamen Rider Fourze and fights the Aquarius Zodiarts as they take their fight outside before he assumes Cosmic States. However, his Limit Breaks have no effect on the Horoscope as Fourze learns that the Aquarius Zodiarts is Erin. Finding Erin at JAXA, Gentaro learns of Erin's reasons for helping Kengo and that she wants to become an astronaut like her father and be able to go into space, refusing to lose that honor to someone like Yuki like her father had.
Seeing he cannot reach her, Gentaro's proposes for Erin to give him her Aquarius Switch if Yuki does beat her. In the second test, with Tomoko and Kengo transferred to another team, the groups are to each assemble a robot within three hours. After Tomoko's group presents a robot modeled after Shun, Yuki and the rest of Team B present a robot cat with Erin livid. Returning to the chamber, Erin finds something that makes her lose it and attempt to hurt Yuki before Gentaro drags her off. However, as Kamen Rider Meteor holds the Libra Zodiarts at bay, Gentaro becomes Fourze to restrain the Aquarius Zodiarts to find out what happened. When Dustards arrive, the two Kamen Riders' fights are brought together.
After loaning Kamen Rider Meteor Storm the Fire Switch, Fourze assumes Cosmic States as the two Kamen Riders use their Limit Breaks. However, the Aquarius heals herself before revealing that Yuki cheated by hiding the piece she needed for the robot design she plan. However, Fourze could not believe Yuki to do such a thing as the Aquarius Zodiarts proceeds to whip him relentlessly.