Koji has a huge crush on Karin and decides that Rosewood School's Annual Costume Party is the perfect time to tell her. Meanwhile, Ikki is Robattling Brass for practice when Karin arrives and invites her friends to the party. Samantha, Spyke, and Sloan overhear Karin and are determined to sneak into the party.
When Ikki (dressed as a puppy) and Erika (dressed as a princess) arrive at the party, they are amazed at the number of people and limousines. This makes it easy for The Screws to slip in unnoticed. The Rubberobos have a little more trouble sneaking in until they shed their costumes for their original rubber suits.
The party is an extravaganza with tables of delicious gourmet foods. Ikki, Erika, and the Screws are enjoying the food as Koji prepares to profess his love for Karin. Koji has instructed his Steward to shine the spotlight on Karin when he gives the signal. Unfortunately, the Steward slips and the spotlight is shown on Samantha who quickly grabs Koji. When Koji runs from Samantha's clutches, he comes face-to-face with the Rubberobo Gang. They insist he hand over his Rare Medals even though he tells them he doesn't have any. Koji becomes enraged and calls for Sumilidon. The Rubberobos, knowing Koji's fear of bugs, summon their Medabot Mantaprey.
A Robottle is announced, but Koji's fear is keeping him from giving commands to Sumilidon. He attempts to flee but runs right into Spyke and Sloan. They too are dressed as bugs! Koji then turns and runs right into a tree and in doing so spills more bugs on himself. At this point, Koji goes nuts! The party is now a fiasco with Sumilidon going equally as crazy.
Ikki and Erika confront Koji's Steward who explains the origin of Koji's phobia. It seems that when Koji was young, he would collect bugs and one day brought home a praying mantis nest. The nest was forgotten until one day when the insects hatched and attacked Koji.
No one is able to calm Koji until Karin approaches him with the news that she and Dr. Aki (who accompanied her) were leaving. He immediately becomes his gracious self again. As Karin drives off in her limousine, Koji regrets his inablility to tell her his feelings. One day Koji... one day.