Masaru Yada is a supporting character in Ojamajo Doremi Dokkān! and a classmate of the main protagonists. He is introduced as a boy in class 3-2, later placed into class 1 during fifth grade alongside Doremi Harukaze and Momoko Asuka. To many of his peers, Masaru is perceived as a delinquent due to his blunt, aloof demeanor and his habit of answering most questions with a curt "not much" or "nothing" (betsuni). Despite this tough exterior, he is genuinely caring and dependable, with several classmates, including Kimura Takao, looking up to him for support.

Masaru is a childhood friend of Hazuki Fujiwara, and their relationship develops quietly over the course of the series. He is acutely aware of her feelings and shows subtle, indirect concern for her well-being, though he often struggles to express himself openly. His motivations are rooted in loyalty to his friends and a desire to pursue his own interests, particularly music. He plays the trumpet in his spare time, a talent inherited from his father, who works as a professional trumpeter stationed in Germany. The trumpet Masaru treasures is a gift from his father, and music becomes a key outlet for his emotions. His family situation includes a stepmother, as his biological mother is not present.

Throughout Ojamajo Doremi Dokkān!, Masaru's role is that of a supportive classmate who occasionally becomes involved in the girls' adventures, though he remains unaware of their magical identity. His development is most visible in his growing openness toward Hazuki and his gradual softening of his prickly demeanor. He learns to trust others and to let down his guard, particularly through his interactions with the main cast and his dedication to his trumpet playing. Notable abilities include his musical skill and his physical coordination, but he possesses no magical powers. His character is defined by internal kindness hidden behind a cool, misunderstood exterior.