Umi is a man of his 30-40's. He has a cat-like motif, like Yama, in which his face does looks like a cat. His eyes are feline-like, his nose is triangle-shaped, and on each of his cheek are 3 stripes which resemble a cat's whiskers.
Umi wears a typical grey tall cap, a sea blue colored happi which has the embroidering of a darker blue wave on it. On his shoulders, there are some red straps which helps in folding his sleeves to his shoulders. On his apron, the kanji for "sea" (「海」?; umi) is present, also spelling his name. Also, he is always seen holding a pair of kitchen knives.
Umi and his restaurant, along with Yama and his cafe, are based on the Japanese story of Chūmon no Ōi Ryōriten (「注文の多い料理店」?; The Restaurant of Many Orders).
The story was created by Kenji Miyazawa. Although not a commercial success, the work came to the attention of poets Kōtarō Takamura and Shimpei Kusano, who admired his writing greatly and introduced it to the literary world.
"Umi" (「海」?) means "sea", which, aside from being his name, is also a reference to where his restaurant is located.
Both Umi and Yama have a cat motif, along with their waitresses. No other people in the Ōkami series have such features.
Umi is the counterpart of Yama, since his restaurant is by the sea, while Yama's restaurant is in Sei'an City. Their name also relates with their locations respectively.