His father, an electrical engineer, took him at age eleven to Karafuto Prefecture on Sakhalin Island, where his grandfather ran a newspaper press.

[1][2] Yamaguchi attended the Third Higher School in Kyoto and joined the student haiku society, where he met poet Sōjō Hino.

Yamaguchi wrote haiku on unconventional subjects such as steam engines, dance halls, skating rinks, board meetings, typists, sports, and parades.

In 1948 he started his own publication, Tenrō ("Dog Star"), where he was joined by his disciple Hashimoto Takako (1899-1963), a poet who was sometimes called the "female Seishi".

[1][2][3] Yamaguchi eventually published over a dozen volumes of haiku, including Kōki ("Yellow Flag", 1935), Gekirō ("Raging Waves", 1944), Wafuku ("Japanese Clothing", 1955), and Setsugaku (1985), and numerous essay collections.