Saeko Mochizuki

Saeko Mochizuki, known as "Osoroshii Baba," is the leader of the Onmoraki-Gumi and the Mentor of the Osaka branch of the Assassin Order

Biography
Saeko Mochizuki is the widow of Kenichi Mochizuki, the former Mentor of the Osaka Assassins. He had died in their old Bureau in an attack by the Yakuza, after they had escaped from Abstergo. They had been Gavin Banks's Mentors when he was a child. Saeko led the Assassin survivors on a mission of revenge against the Yakuza, and then took over the gang.