He is the tsukkomi of the manzai duo, Yoiko, with his partner Shinya Arino.
Hamaguchi and Arino were classmates that graduated high school and formed a manzai duo in 1990.
[1] The duo would make their first major televised appearance on Mecha-Mecha Iketeru!
[2] Hamaguchi was born into a family that owns a coffee shop called "Hamayū" (はまゆう) in Konohana-ku, Osaka, named after the poisonous spider lily from his grandfather's love of lily flowers on the beach.
[3] In 2013, Hamaguchi began dating the gravure idol Akina Minami.