Masa, called Marvin in the English dub, recurs as a bullying accomplice to Ted and Kenny, forming a trio that torments Yuna and her friends. He sports light brown skin, black hair, narrow eyes, a yellow shirt with blue sleeves, tan shorts, and an orange bracelet on his right wrist. The group employs theft, physical intimidation, and targets vulnerable figures like Taro, often escalating violence beyond predecessors in the franchise.

Their dynamic centers on appeasing Penny’s demands, whether dancing in costumes for her performances or aiding schemes like kidnapping Mr. Stenchy to satisfy her obsession with the experiment. After Penny excludes Ted from a Christmas party, Masa and Kenny offer half-hearted consolation before abandoning him to pursue her approval. This pattern fractures when Ted rescues Penny, sparking reconciliation and a joint celebration.

During a school field trip, Masa and his friends harass Taro until Yuna intervenes. On Valentine’s Day, they exploit Kenny’s romantic desperation, inadvertently unleashing Experiment Hunkahunka’s chaos. Temporarily swayed by the experiment’s influence, they chase Stitch before its effects subside. By the second season’s climax, Masa reacts viscerally to Stitch’s presumed sacrifice, weeping with relief when Stitch survives a black hole’s destruction.

Though his past remains unexplored, Masa functions as a secondary antagonist emphasizing group hierarchies and sporadic peer loyalty. His development hinges on collective actions over personal evolution, with rare moments revealing underlying camaraderie beneath his aggressive exterior.