Mira Shifuto's about to get married to a man she doesn't want to when she's suddenly whisked away by a deliveryman.

Ishiro still won't acknowledge Mira as a Boonboomger as the team has to deliver classified documents to a foreign ambassador.

Mira goes out on her first solo delivery while a clock-themed Hashiriyan tries to stop everything that moves.

After saving a child from getting hit by a truck, Mira is arrested by Officer Akuse and brought in for questioning by the International Space Agency.

Taiya reveals his real intentions to form the Boonboomgers, which is to participate in the "Big Bang Grand Prix", the biggest and most important race of the entire universe, while fighting the Hashiriyans was not in his original plans.

Taiya is seriously wounded after his fight with Mad Rex and Shirabe informs the team that the ISA decided to have the Boonboomgers disbanded and their equipment confiscated.

Taiya makes a special delivery to an old friend who inspired him to become a deliverer in the first place. Meanwhile, Cannonborg, another team captain arrives to assist the Sanseater in taking over Earth.

The Boonboomgers meet Sakito Homura, a mysterious man who possesses the same powers as them, able to transform into Bun Violet and whose intentions are unknown.

Sakito makes an offer to Taiya to join the team. Meanwhile, Sakito's partner Byun Diesel is an old acquaintance of Boondorio and wants to meet him again, but Boondorio refuses and the past between them is revealed.

At the Hashiriyan's request, Sakito starts trying to get rid of the Boonboomgers! Taiya asks him, "Why did you abandon the earth?" But...!? Will Sakito turn out to be a friend or foe!?