Rantaro Kiyama

Tarou Kiyamaran (Japanese: 黄山乱 太郎 Kiyamaran Tarou), also known as Boss (Japanese: クミチョー Kumicho) is a character from Hiro Morita's Beyblade Burst Manga series.

Beyblade Burst (Manga)
Tarou Kiyamaran debuts in the first chapter as the first person ever to be challenged by Valto Aoi. However, their first battle ended up in disaster as Valto's wrong launch broke the statue of the school's founder. As a result, both Tarou and Valto were punished by their teacher.

Personality
Tarou often refers to himself as "Boss" and is good at sneaking things in and out of their school's strict regulations.

Trivia

 * His family name means Yellow Mountain Rebel