Masuda has been Ryo Amakusa's close friend since their middle school days. He works freelance as a cameraman. Physically, he possesses an average build, unkempt black hair, glasses, pierced ears, and favors casual clothes—typically sporting an orange hoodie, gray pants, and green sneakers. Privy to Ryo's personal life, Masuda specifically learns of Ryo's pursuit of Ichika Arima through rumors. He directly confronts Ryo at a bar to verify the situation. During this exchange, Masuda engages in lighthearted teasing about Ryo's motivations while offering to put in a good word with Ichika. This leads to a late-night phone call where an angered Ichika complains about the disturbance, prompting Masuda's subsequent apology. His professional work brings him alongside the main characters as their photographer during a school trip to Okinawa. This role allows him casual observation of the shifting dynamics between Ryo and Ichika. Later, Masuda's involvement deepens as he participates in discussions questioning the social appropriateness of Ryo's relationship with a high school student. He joins a confrontation urging Ryo to consider potential consequences. Throughout the series, Masuda remains Ryo's primary confidant and sounding board. Their interactions, mostly occurring in casual settings like bars, focus on relationship developments. He communicates straightforwardly when challenging Ryo's choices, consistently upholding their long-standing friendship. No substantial expansion of his personal background or independent character development occurs beyond this established role. His narrative presence stays consistent as a secondary character facilitating dialogue about central relationship conflicts. No official information exists regarding expanded appearances in other media beyond the core series.