Mamoru Martial Arts began during the pandemic in 2020, as just an idea. When founder Alexander Greenfield realized he was not moving physically as much as used to, he felt prompted to return to the movement and discipline of judo. As Alex describes it, he “heard the voice of the Spirit” affirm this impression. A few days later his dad called and added confirmation was granted when he not only encouraged Alex to build a dojo, but insisted on being the first investor by purchasing the first mats.

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The early months were small, with only a few students at a time. But as word spread—especially among BYU–Idaho students—the dojo steadily grew. Today, Mamoru Martial Arts serves around 100 students and continues to expand its offerings, including the recent launches of taekwondo, yoga, and now Tai Chi.

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The school’s name honors Alex’s first sensei, Mamoru Shimamoto, a distinguished judo champion from Japan whose mentorship deeply shaped Alex’s approach to teaching. The name “Mamoru” means protector, which is a fitting reflection of the school’s mission and values.

 

Throughout this journey, Alex has consistently felt the Lord’s guidance in the dojo’s growth and in the strong community that has formed—one where students build confidence, discipline, and meaningful connections. What began as an impression during a time of isolation has become a thriving martial arts dojo—a place of connection, discipline, and personal growth, with many chapters still ahead.