Tanabe Tomomasa was a student of Yanagawa Naoharu. There were two generations of this name, and they were also closely associated with Haruaki Hogen who was also a student of Naoharu. According to the entry in Marcus Sesko’s ‘The Japanese Toso-Kinko Schools’ even Kano Natsuo held them in high regard. I’ve seen a signed and dated tsuba by Tanabe Tomomasa, 1861.