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Mika is the priest of the Moon Shrine and the purifier for the travelers if they would visit the shrine. He is always waving the 'tamagushi' since of his responsibility to guard the Moon Shrine and cleanse it from a greater evil or impurities. When Amaterasu is carrying Kushi on its back, Mika waits in front of the shrine, he tells to Amaterasu to be careful since the day is utterly despicably horrifying for life's experience. He stills prays that the land of Nippon is safe from evil.
Like previously, Mika is still devoted to the Moon Shrine, yet now he highly praise Amaterasu. When Chibiterasu meets him for the first time, Mika complains that he had been robbed by demons, who took away scrolls about Amaterasu, which are are scattered everywhere in Shinshu Field. Still, Mika is responsible for the cleansing and purifying the impurities around the Moon Shrine even if the dreaded Orochi has fallen.
Spoilers end here.
"You know, you really remind me of the great Shiranui. You look exactly like the sacred statue in Kamiki. Let us pray the great Shiranui is looking over you from on high. I've entrusted the wanted list to you. Good luck!"
Mika and Yatsu are the only notable Shinto Priests in Ōkami, their attire is highly similar except for the color and the headgear. As a Shinto Priest themselves, they both wield the Gohei.
While Mika's headgear resembles the roof of the Moon Shrine, Yatsu's resembles the windmill on top of Gale Shrine.