Ishiro trails Jou, thinking his overly serious policeman persona might just be an act when a toilet-themed Hashiriyan starts forcing the truth out of people. Meanwhile, Taiya has to deal with a new foe.

The Boonboomgers are afflicted by a mysterious phenomena that leaves them apathetic, while Genba approaches Itasha of the Sanseater with unknown intentions. Meanwhile, Cannonborg completes his secret weapon to counter Boonboomger Robo.

On Tanabata day, everyone is having fun, but only Boonboom remembers his bad past with the word "Milky Way". Then, a new Guruma appears, and Taiya is in the biggest trouble ever...!?

Cannonborg is on his last legs, initiating a plan to destroy Earth from space.

Genba has a heart-to-heart with someone he least expects. The Boonboomger use a new invention to transform into a powered-up form to confront Mad Rex.

The Sanseater are greeted to the arrival of Wayway Yarucar, an elite member of the Yarucar race, as the Hashiriyan prepare for Spindor's arrival.

Spindor is given the offer of the Earth's soccer league being part of his own Big Bang Soccer league, which Sakito and Genba take issue with.