Surname Ryoichi (Ryoichi 
, 良一 , 亮一 ) , around the world, is quite a rare family name. The family name Ryoichi is characteristic of Japan, where it is quite a rare surname, Singapore, where it is a rare surname, and Cambodia, where it is a very rare surname. Measured by absolute frequency, it most frequently occurs in Japan, China, and Indonesia. Also, Ryoichi is the forename as well as the last name.