Mamoru Martial Arts started in 2020 when founder Alexander Greenfield felt spiritually prompted to return to judo during the pandemic. His father confirmed this direction by becoming the first investor, purchasing the dojo's initial mats.

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Beginning with just a few students, the school has grown to serve all around the community from BYU–Idaho students, and families including individuals from the local Rexburg community and surrounding areas including Sugar City, St. Anthony, Ashton, and Rigby. The school now offers judo, taekwondo, and yoga! Creating a welcoming space where college students train alongside local families.

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The school is named after Alex's first sensei, Mamoru Shimamoto, a distinguished Japanese judo champion. "Mamoru" means protector, reflecting the school's mission to help students build confidence, discipline, and meaningful connections. What began as a pandemic impression has become a thriving community bringing together students and families from across eastern Idaho, with continued growth ahead.