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 Hashilien 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.

Jou wants to become a Boonboomger, but Taiya rejects him, saying he doesn't have what it takes just yet.

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.

Boonboom has fallen in love. Mira, as a delivery person, decides to take Boonboom to the person he loves. Boonboom falls in love with someone he never expected...!? Meanwhile, Taiya gives something to Genba.

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 Madrex and Shirabe informs the team that the ISA decided to have the Boonboomgers disbanded and their equipment confiscated.

Genba has his first solo delivery job for the ISA. Worried about him, Mira decides to tag along, when the Sanseater attack the duo.

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.

Taiya runs into a certain familiar Engine and takes on the job delivering him to his partner.

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.

After Genba having successfully activated BoonBoom Safari, Ishiro and Mira pay a visit to an aquarium looking for inspirations to activate BoonBoom Marine, when the Sanseater return with a fixed-up Boonboom Killer Robo, eager for a rematch.

Jou finds a monster created by the Hashiryan who refuses to attack humans and befriends him, determined to protect his new friend from the enemy.

The Boonboomgers meet Sakito Homura, a mysterious man who possesses the same powers as them, able to transform into Boon 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!?

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