Miyama Sana is the main heroine of Gundam Breaker M and a key figure in Gundam Breaker Battlogue. As the president of the Kanami High School Gunpla Club, she possesses a bright, active personality and strong initiative. She is passionate enough to persistently persuade the protagonist, Ryusei, to save the club from the verge of being disbanded. While she underestimated her own skills early on, she grows into a talented fighter through interaction with her teammates. Her personal machine is the Gundam Perfect Strike Freedom. Her primary armaments include the Schwert Gewehr anti-ship sword for powerful close-range destruction, the Agni for long-range strikes, the Dragoon System (funnels) for multi-angle attacks, and the Indra special unit for capturing or electrocuting enemies, allowing her to demonstrate overwhelming combat power at all ranges.

Fudo Ryusei is the protagonist of Gundam Breaker M and the strongest fighter who won three high school titles after entering the scene at Miyama Sana's suggestion. His personal machine, the Gundam Helios, is equipped with powerful armaments such as the Balaena Kai Twin Beam Cannon, Arondight Beam Sword, and Palma Fiocina. His ultimate move, the Sextuple Cannon, is a technique that opens all gimmicks to unleash an overwhelming simultaneous volley.

Aizen Touma is a major character in Gundam Breaker M and Battlogue, serving as a friendly rival to the protagonist, Fudo Ryusei. He has a strong sense of responsibility, choosing to transfer schools to aim for a professional fighter career to support his livelihood. He pilots his personal machine, the Gundam Livelance Heaven. He is characterized by a very active and daring battle style, utilizing his main weapon, the Valkyrie Rod, and the Active Cloak, which combines defense and mobility.