Masu (「真澄」?; Masumi) is a minor character encountered in Ōkami. A samurai wandering the streets of Sei'an City, he always has a list of demons with him, which he plans to go to Ryoshima Coast and hunt them down.
Not much is known about Masu's personality, but it is heavily implied that he is a serious man, as when he refuses to give Amaterasu his list of demons, and even up to the point of attacking the Sun Goddess, should she headbutts him. However, when Masu is drunk, his hangover will prompt him to do whatever that is told, and in the case of Issun's request, gives him the Monster Manifest that he normally keeps with him.
As a person of the samurai class, Masu is always seen in an attire consisting of a yellow kimono and a purple hakama, and always with him is his katana, whose sheath is made of traditional lacquered black wood, and the handle is of a slighter gray. His face is quite large, and his mustache is kept as thin strips, and he also has a small beard. As a samurai, Masu also has a flag on his back, and his hair is tied into a ponytail, with the hair on his temples pointed high.
Masu is first encountered during Amaterasu's quests at Western Nippon, when an acrid and poisonous fog from an unknown source shrouds the entire of the capital city. The samurai is found sitting just in front of the gates to the Aristocratic Quarter, lamenting about the sickness plaguing the city, and Queen Himiko's incredible holy powers, but don't do a thing about the unnatural fog shrouding Sei'an City[Citation needed].
If Amaterasu headbutts Masu, he will attempt to attack her with a dashing slash, signified by his stance, his right hand on the katana's handle. The attack itself wouldn't do any damage nor costs her Godhood and can be easily evaded by any means, but should it connects, Amaterasu will be stunned for a brief moment.
The way that Masu wields his katana may suggest that he uses the Iaido martial art in combat.
Masu is one of the very few characters in the entire Ōkami series to have their names in the original Japanese versions written not in katakana, but entirely kanji. Naturally, this means that Masu bears some sort of cultural relevance or importance, though this is not the case for the main characters who are based on real life mythology themselves.