Masa, called Marvin in the English dub, recurs throughout the *Stitch!* anime series. As one of Kenny's closest friends, he forms a trio of bullies with Kenny and Ted. This group frequently targets Yuna and her friends, employing tactics described as more violent than Mertle's gang from the original *Lilo & Stitch*, including physical aggression and theft directed at vulnerable peers like Taro. Physically, Masa possesses light brown skin, black hair, and narrow eyes. His typical attire consists of a yellow shirt with blue sleeves, tan shorts, and an orange bracelet on his right wrist. His appearance and secondary bully role draw noted parallels to Yuki from the original *Lilo & Stitch* series, particularly in their shared narrow-eyed design, dark skin tone, and green clothing elements. Masa's actions are frequently motivated by a desire to appease the wealthy and demanding classmate, Penny. For instance, in "A Stinky Episode," he helps Penny kidnap Mr. Stenchy after her infatuation with the experiment, leading to a confrontation with Stitch and Yuna that ends with Masa, Kenny, and Ted drenched in Mr. Stenchy's foul odor. Similarly, during "We Wishy You a Washy Christmas," Masa and his friends cater to Penny's demands to secure invitations to her Christmas party. When Ted accidentally ruins Penny's dress, causing his exclusion, Masa and Kenny initially comfort Ted but abandon him when Penny summons them; they later reconcile with Ted at the party after he saves Penny from a monster. In "Switcheroo," Masa joins in bullying Taro by throwing his insect book, dismissing the act as trivial when Yuna intervenes. Later, on a school field trip, Masa and his friends listen to a teacher's lesson about insects, their prior harassment of Taro underscoring their recurring antagonism. The episode "Hunkahunka Burnin' Angel" shows Masa supporting a distraught Kenny over lacking a Valentine's date. After Stitch uses Experiment Hunkahunka to attract Sasha to Kenny, Masa celebrates his friend's apparent success. When Sasha's obsession manifests, Masa flees with the group. He later falls under Hunkahunka's influence himself, developing an infatuation for Stitch until the effect is neutralized by water. A moment of emotional vulnerability surfaces in the second-season finale when Masa, alongside others, tears up witnessing Stitch survive a black-hole explosion, suggesting a capacity for empathy contrasting his usual antagonism. Inconsistencies in the English dub credits occasionally list his original Japanese name, "Masa," instead of "Marvin," though this does not reflect narrative changes.