Within Motoha Yoshin Ryu JuJutsu, the Japanese do not use a coloured belt system or perform gradings until Shodan (Beginner Dan, often referred to as 1st Dan). Those training start wearing a white belt and transition directly to black if they pass the grading.
The concept of coloured belts and gradings before black belt level is generally a western, modern addition to many martial arts, with each style often having its own different choice of colours and progression between these.