百地 蝶治郎

The son of the late leader of Iga, Momochi Tanba, the protagonist's cousin.
After losing his family and clan in the Tenshou Iga War at the age of five, he joined Kouga with his surviving people.
Since he is the son of the Head Shinobi of the fallen Iga, he's naturally observant and calm. 
His skills as a Shinobi are eminent in Kouga, as he's also a teacher for Enju and the others.