TOKYO >> The neighborhood of low-rise residences and small businesses in the Edogawa section was just beginning to stir in the low-40-degree temperatures of the early morning.

But inside the largely unheated ground-floor room of a four-story white building just off the main street, young sumo wrestlers were already sweating profusely, some of the earthen practice ring caked on their legs and torsos.

Under the large portrait of the stable’s master, former yokozuna Musashimaru, they were well into the day’s labor in preparation for the New Year’s Tournament that opens Sunday.

The wooden-framed portrait denotes a sumo tournament title and once hung inside the Kokugikan, where he won the Emperor’s Cup, the Mecca of the sport.

That it now overlooks the Musashigawa sumo-stable practice ring is meant to serve as inspiration for the 16 apprentices, ages 16 to 22, who hope to someday follow in their master’s large footsteps.

If that isn’t enough to push them though the day’s toil, then the man himself, Musashigawa stablemaster Fiamalu Penitani, 45, sits sternly perched on a wooden ledge at the ring’s edge, scrutinizing their performances and barking instructions.

Later, as the session winds down, one by one, they will step to the side of him, bow reverently, take his advice, shout their acknowledgment and bow again before departing his presence.

It is the way things were done when Penitani, a former Waianae High football player, joined as a raw recruit in 1989. “It is the way it has always been done,” Penitani said of the centuries-old sport.

He is one of only two foreigners (Jesse Kuhaulua, the former Takamiyama, was the other) who have risen to the ranks of stable owners in the Japan Sumo Association, the ruling body for Japan’s national sport.

Penitani, who will soon begin his 28th year in sumo, remembers the day he first flew to Japan to take up sumo. “My mother grabbed on to me so that I wouldn’t go,” he said.

But he eventually did leave, arriving in Tokyo with little knowledge of Japanese or sumo. One of the first things he learned was that the stable owner is lord and master. “Never,” he says, still shaking his head at the thought, did he imagine someday becoming one himself.

The plan was to try to find success in sumo, save some money and then return to Hawaii. But after carving out a lucrative 14-year career in the ring, during which he managed to become the second foreigner (after Chad Rowan, the former Akebono) to ascend to the exalted rank of yokozuna and win 12 tournaments, things changed.

The once-alien world of sumo became his life. After his retirement in 2003, Penitani, by virtue of his rank, gained elder status and became a coach in the stable. In 2013, with his wife, Masami, he became invested in it, opening his own stable and recruiting young apprentices.

The couple and their 2-year-old son, Joey, live up above the dorm inhabited by the eclectic collection of sumotori. Senior among them by virtue of rank earned in the ring is Penitani’s 6-foot, 319-pound nephew, Mamo Penitani, who has reached the makushita division, fourth highest and one below the salaried ranks, in three years.

Recently Musashimaru has also taken on Ichiro Young, a half-African-American, half-Japanese athlete from Houston and Ryutaro Tokuda, a 6-3 271-pounder from Kagoshima who joined after winning junior high championships.

“Sumo is a hard life, but he (Musashimaru) has shown that if you work hard and get to the top what it can be like,” Mamo said. “That’s where we’re all trying to get to.”

Reach Ferd Lewis at flewis@staradvertiser.com or 529-4820.