Kawachi was a student at Kanto Gakuin University when Yujiro Ishihara, one of his neighbors in Zushi, Kanagawa, invited him to join the Nikkatsu studio.

[1] He made his debut in A Slope in the Sun (1958) playing Ishihara's younger brother.

[2] The studio initially sold him as one of the "Bad Trio" along with Akira Kobayashi and Tadao Sawamoto.

Kawachi eventually left Nikkatsu for the Toei Company, and co-starred in the 9-film Mamushi kyōdai series with Bunta Sugawara in the 1970s.

[2] He was also known for his recurring role as Inspector General Sawaii in Ultraman Tiga.