Kōta Kōga is the main protagonist of the anime Cap Kakumei Bottleman DX. He is a twelve year old boy whose most recognizable feature is his bright red hair. He is described as a cheerful, refreshing, and passionate hot-blooded boy. His personality is characterized by high energy and straightforward optimism. He becomes deeply engrossed in the world of Bottle Battles after a chance encounter with the mysterious new Bottleman known as Colamaru DX. This discovery awakens him to the fun and exhilarating thrill of the sport, and he quickly becomes obsessed with it.

Kōta's primary motivation is his burning desire to improve and face strong opponents. He is naturally talented, possessing an innate aptitude for Bottle Battles, and his battling style is straightforward and power oriented. He is also supported by his best friend and aspiring influencer Ponta Hayari, who provides guidance and commentary during his early matches. A key relationship in the series is his fierce yet friendly rivalry with Ryo Hokari, whose calm, analytical, technical precision contrasts directly with Kōta's raw power and impulsive nature. Kōta also receives mentorship and technical support from the scientist Kaori Hakase.

Throughout the series, Kōta undergoes significant development, evolving from a novice enthusiast into a top tier competitor capable of challenging the elite of Bottle Island. He learns to balance his impulsive nature with strategic thinking, and he eventually masters the DX System. His core drive is to protect the true spirit of the game against those who seek to exploit it for profit. His primary Bottleman partner is the phoenix-themed Colamaru, which specializes in powerful drive shots.