Masa san
Name in Japanese
Rōmaji Translation Masa
Appears in Anime
Voice Actor (Japanese) Katsuki Murase, Shūichi Ikeda (young Masa Shiranui)
Voice Actor (English) Christopher Sabat (English)
Personal Info
Gender Male
Affiliation Seto Group

Masa ( Masa?) is a member of the Seto Group and the right hand man of Gozaburo Seto.


Masa is a tall, handsome and muscular man with an Afro hairstyle. He also wears a suit and tie mostly throughout the series. He is always seen wearing sunglasses, so it is unknown what colors are his eyes.


Masa is the only one apart from Ren Seto who does not object to the engagement and sometimes even gives advice to Nagasumi Michishio. Usually, Masa is portrayed a silent man but due to his highly good looks he mostly captures peoples' hearts such as making Nagasumi's Mother fall for him just by looking at her and even making Nagasumi admire him. However, when he drinks he tends to talk too much and reminisce. Masa cares a lot for his sister Akeno Shiranui and he is very protective of her often beating up those who are aggressive towards her. 


Masa also transfers to Nagasumi Michishio's school, becoming his math teacher (whose word problems tend to describe to the mathematical aspects of underworld gang operations). There is a running gag of Nagasumi displaying an attraction towards Masa since their "first kiss" in the first episode.

Powers and Abilities

Masa is one of the few Merfolk who is not afraid of cats as he explained that he decided to overcome the fear as a child.



  • The name Masa means "government" (政).
  • Later in the series, he is revealed to be the long-lost brother of Akeno Shiranui.
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