Why is Oma Kokichi called Tojo's mother?

Oma Kokichi called her mother Tojo because she was brought up by Tojo. Oma Kokichi, the character in the game "Breaking V3 on the New Bullet", tells the background story of the game. Oma Kokichi was abandoned when she was very young, and was later adopted by Tojo, so Oma Kokichi was called Tojo's mother.