Earth Academia Japan Branch Head Professor Kenzo Mukai (向井 健三博士 Mukai Kenzō Hakase?) is the Japan branch chief of the Earth Academia dedicated to the pursuit of justice. He fell in love with Sayuri, a plant researcher, many years ago, but left her. When they meet again during Rasbelga's attack, Mukai donned a special armor and donned the title of "Mukaider K3" (ムカイダーK3 Mukaidā Kē Surī?, 38) to save her, with attacks like Mukaider Magnum (ムカイダーマグナム Mukaidā Magunamu?), Mukaider Kick (ムカイダーキック Mukaidā Kikku?), Mukaider Punch (ムカイダーパンチ Mukaidā Panchi?), and Mukaider Feint (ムカイダーフェイント Mukaidā Feinto?). He works as a "mentor" for the B-Fighters, usually working at Earth Academia to assist the team by leading research on Jamahl's warriors and developing new weaponry and vehicles for the B-Fighter