The aim is to promote sportsmanship, introduce youngsters to Japan's traditional sport and raise environmental awareness.
Beach sumo was created by Tamakairiki, a former sumo whose real name is Yukio Kawabe.
"Kids only see sumo on TV, so this gives them a chance to experience it up close," he said.
Sumo has been criticized in recent years over a variety of problems: the death of a teenage wrestler, marijuana use and the attitude of some of its stars.
Professional sumo is a sport with a strict hierarchy. Women aren't allowed to compete and many newcomers are unable to cope with its rigid rules.
The number of new wrestlers has declined in recent years and the sport is increasingly dominated by foreign wrestlers like grand champions Hakuho and Asashoryu, of Mongolia.
Tamakairiki hopes his approach will lure more young Japanese.
"We haven't had anyone turn professional yet, but you never know," Tamakairiki said. "The kids really enjoy this and it teaches them to deal with physical contact in a safe environment."
Before each tournament, Tamakairiki goes through a list of do's and don'ts, which include punching, pulling hair and, of course, kicking sand in an opponent's face.
Like professional sumo, opponents always bow to each other before and after every bout and throw salt to purify the ring.
Tamakairiki's beach sumo tournaments are run in conjunction with Beach Life Japan, an organization set up by Shoji Setoyama, a former beach volleyball player who represented Japan at the 1996 Atlanta Olympics.
"Beaches are threatened by trash and rising sea levels," Tamakairiki said.
"We teach kids about beach preservation after every tournament so they come away with an appreciation of beaches and sumo."