Maestru is the leader of a singing group that meets every week at the community center. His name is a play on the word "maestro." He is a good musician himself and can play a few instruments, like the keyboard and piano. His favorite students are a pair of nerdy kids named Ray and Mimi, who follow everything he says and try their hardest to master every song. Along with his job as a singing teacher, Maestru works as a coordinator for local stage plays.
In "Sing!", Maestru finds his new least favorite students when Oobi and Kako join his group. At first, the boys goof off and interrupt Maestru when he's trying to teach. Maestru gets a bit impatient with them, but he decides to sit them down for a talk. He explains the benefits of singing together as a team, and the boys promise to stop fooling around. They end up impressing Maestru by singing a "round" with Ray and Mimi.
In "Theater!", Maestru directs a musical version of Little Red Riding Hood, starring Uma as Little Red. He introduces the show by telling everyone in the audience to turn their cell phones off. Later, he walks over to his keyboard and uses it to play all of the show's background music.
Maestru is a tall hand puppet with fair skin and blue-green eyes. His hair is black with streaks of gray, and it's styled to resemble the hairstyle of the famous composer Beethoven. Maestru's index finger is always extended and he uses it a conducting baton. He always wears a black bow tie around his wrist.