Master Kumiko (also known by just her first name, Kumiko) is Crash Man's childhood friend and former mentor. She is 14 years old, and despite normally being calm and collected, she resorts to a girlish personality when her friends are around. Violet Rune is jealous of her, but only because of her relationship with CM.
Kumiko is slightly shorter than Crash Man, but very fit.
She has tan skin, and short strawberry-blonde hair. It is kept in short spikes at the top, and the back of her head has the spikes drooping down just to the middle of her neck, where her hair ends. Her chest is relatively flat compared to other female characters of her age.
- She may be of Vietnamese blood, as Kumiko is a Vietnamese name.