Yamaguchi, through his decades-long involvement in professional wrestling, was more than just a manager. Among other endeavors, Yamaguchi played a role in the founding of Frontier Martial-Arts Wrestling (FMW) in the late-eighties, as well as the weekly Japanese wrestling publication Gong Magazine.
For a number of years, Yamaguchi serviced WWE as its talent liaison to Japan, and was instrumental in brokering the deal to bring Dick Togo, Men's Teioh, and Sho Funaki into the company in 1998. Yamaguchi performed as their manager, as well the manager of Taka Michinoku when he reunited with his former stablemates later that year following a heel turn.
Yamaguchi remains part of pro wrestling lore for a comical moment from that summer. After Val Venis was revealed to have been sleeping with Yamaguchi's kayfabe wife, the irate manager threatened revenge by using a katana to slice a large sausage in half, before memorably exclaiming to Venis, "I choppy choppy your pee pee!" He, with Kaientai's assistance, almost made good on the threat before Venis was saved by real-life genital mutilation victim John Wayne Bobbitt, in one of those "only in wrestling" moments.
Our condolences to Mr. Yamaguchi's family and friends.