Yoiyami Ryuuzen

Yioyami is the oldest of four dragon siblings, and was first in line to be the next Dragon King, but because he was born without a gyouki (a stone which contains a dragon's power) he was deemed not suited to be king. Yoiyami was the one to give Sakura's siblings the Dragon's Fruit to heal her after a car accident, and acted as her bodyguard throughout the manga. For some time Yioyami's powers were inhibited by a special charm bracelet. When wearing this bracelet he took on the persona of Yuuki-sensei. He later develops romantic feeling for Sakura.