Sori

A high-ranking spy and ninja obsessed with art, driven into political intrigue in order to gain access to European art, which is contraband in that period. Master Sōri has a daughter named Tatsu and is a childhood friend of the Asano clan. Rin goes to him hoping he will be another sword against Ittō-ryū. He refuses to offer any help at first but is soon able to provide Rin with thirty ryō. He later assists Manji after he is injured, and informs him about who is behind the Mugai-ryū. Also hires Magatsu to watch over his daughter while he is away painting, and is later revealed that may have greater interest in Magatsu (to which Manji notes after his conversation with Magatsu in volume 12, Autumn Frost).

He first appears in Genius part 1. (Source: Wikipedia)