Age: 32
Birthday: February 6
Height: 169 cm
Weight: 58 kg

Yamazaki is a spy, whose specialty is naturally gathering intelligence. Yamazaki is often caught by Hijikata playing badminton by himself, and he is subsequently beaten. He is often seen cosplaying as a badminton-playing version of Echizen Ryoma from The Prince of Tennis. In episode 62 he was caught saying "Mada mada dane," which is Ryoma Echizen's catchphrase.

His role as a ninja is roughly based on Yamazaki Susumu, but is never really exercised besides one unsuccessful attempt to spy on Gintoki. Despite having a rivalry with Shinpachi, they most often see eye-to-eye out of their respective groups.

Despite his lack of screen time, he came in 9th in the Gintama character popularity poll. But even with his popularity, Sorachi has clearly stated that he will never be on a cover of a Gintama volume.

His name is based on the historical Yamazaki Susumu.