World-Class Instruction

Meet Our Coaches

Our team brings decades of combined experience in competition and instruction, united by a passion for developing students of all levels.

HEAD INSTRUCTOR

JON CALESTINE

Jon Calestine is a Brazilian jiu-jitsu black belt under Daisuke Yamaji and Eddie Cummings, and was also one of Eddie Cummings' primary training partners during Eddie's peak competitive years. Widely regarded as one of the top 145-pound grapplers of his generation in the submission-only professional grappling circuit, Calestine is best known for his wins at the Eddie Bravo Invitational, Onnit Invitational, Sapateiro Invitational, and Finishers Sub-Only. Known for his technical precision and deep understanding of modern submission grappling, he has spent years training and competing alongside some of the most respected athletes in the sport.

CREDENTIALS

• Black Belt under Daisuke Yamaji & Eddie Cummings

• Eddie Bravo Invitational Champion

• Onnit Invitational Champion

• Sapateiro Invitational & Finishers Sub-Only Champion

INSTRUCTOR

RONNIE RODRIGUEZ

Ronnie is a Brazilian jiu-jitsu brown belt under Jon Calestine and a former Division I collegiate wrestler who began his jiu-jitsu journey as a white belt under Jon just six years ago. Since then, he has rapidly established himself as a dominant competitor, earning numerous local titles including CS/R Invitational Champion and multiple LIJJN Super Fight Championships, among others. In addition to his success in grappling, Ronnie is a professional personal trainer and accomplished MMA fighter. Known for his high-level athleticism, competitive experience, and well-rounded skill set, he brings both technical expertise and real-world fight insight to the mats.

CREDENTIALS

• Brown Belt under Jon Calestine

• Former Division I Collegiate Wrestler

• 3rd Place IBJJF Pans

• CS/R Invitational, Grapple in the Temple & Submission Battleground Champion

HEAD INSTRUCTOR

JEFFREY KIM

Jeffrey Kim is a Brazilian jiu-jitsu black belt under Daisuke Yamaji, widely respected for his decades of experience and deep expertise in leg locks. A seasoned grappler who was already a purple belt when Jon Calestine first began training, Kim has played an instrumental role as one of Jon's primary training partners, particularly in preparation for high-level competition. Known for his technical precision and advanced understanding of lower-body submissions, he brings a wealth of knowledge to the mats and is regarded as a highly respected figure among training partners and students alike.

CREDENTIALS

• Black Belt under Daisuke Yamaji

• Multiple NAGA Championships

• More than a decade of Grappling Experience

• Leg Lock Specialist

INSTRUCTOR

KEVIN RAMKISHUN

Kevin is a Brazilian jiu-jitsu purple belt under Jon Calestine and a former New York City high school wrestling champion. Born and raised in South Ozone Park, Queens, he began training Brazilian jiu-jitsu in 2017 while finishing law school after being introduced to Renzo’s in Williamsburg through his wrestling background. A college wrestling team captain in his senior year, Kevin carried his competitive mindset into grappling and developed a style that blends strong wrestling fundamentals with modern jiu-jitsu concepts. Known for his relatable coaching style and technical approach, he focuses on teaching practical, effective techniques while helping students understand positional strategy and submission threats. Kevin takes pride in creating a positive and supportive training environment where students of all experience levels can improve their skills and enjoy the process of learning jiu-jitsu.

CREDENTIALS

• Purple Belt under Jon Calestine

• NYC High School Wrestling Champion

• Former Collegiate Wrestling Team Captain

• Wrestling-Based Jiu-Jitsu Specialist