Complex sentence: When Mitsuzane tries to take Mai away from the Armored Rider force, Peko tries to stop Mitsuzane from being reckless however, Peko is recently beaten brutally by the Over Lord Shinmugurun until Mai had no choice to follow Mitsuzane and spare Peko's life.
Split into simpler sentences: When Mitsuzane tries to take Mai away from the Armored Rider force, Peko tries to stop him from being reckless. However, Peko is attacked by the Over Lord Shinmugurun, leaving Mai no choice to go with Mitsuzane to spare Peko's life.