Ono No Takamura
Ono No Takamura is one of the confirmed allied characters in Onimusha: Way of the Sword, joining Musashi Miyamoto in his fight to clear the Genma from Edo-era Kyoto.
A Second Gauntlet Bearer
Capcom has confirmed that Ono No Takamura's in-game counterpart is also an Oni Gauntlet bearer, which puts him in the same supernatural weight class as Musashi. Historically, the real Ono No Takamura was a Heian-era scholar and poet, and the game leans on that scholar framing while reworking him as one of Musashi's supernatural peers.
Role
Capcom has described the allied cast as contributing different kinds of support to the party. Ono No Takamura provides magic, sitting between the raw power of Lady Oni and the eccentric support brought by Izumo No Okuni.