They are barefoot, despite the freezing temperature, and sit impassively with ramrod backs, staring ahead. Through a gap in the gym's tired sliding doors they can see snow-capped Mount Kinpoku on the other side of the bay. One by one, they raise their arms high and hit the drums with metronomic regularity. Four hours in the morning, four hours after lunch.
None of them has ever heard of Clive James and his send-ups of Japanese television's 'endurance games'. Even if they had, they wouldn't see the joke. They have set their hearts on joining Kodo, the internationally acclaimed drumming group that lives communally in Ogi, a village half an hour down the coast.
Kodo has been based on Sado, an island off the north coast of Japan, since 1970. The group plays the taiko, a traditional Japanese drum, and is known around the world for its thunderous, visually striking performances. Their unique style is based on ancient Shinto rituals, in which drums were used to settle disputes (the drummer who could play the most intricate patterns would get his way) and to mark out boundaries (village limits were determined by how far the drums could be heard).
Today, there are literally hundreds of amateur taiko groups in Japan, which are hugely popular with adults and children alike. None, however, has achieved anything like the success of Kodo. Its year is divided between touring (it has just completed a three- month tour of the United States and will appear in London in May), and living communally on Sado.
Despite its international reputation, Kodo is still wary of the outside world. The group has often been misunderstood by the Western media, which loves to depict group members as belligerent kamikaze types, or part of a religious cult. It was only after protracted talks between senior members that a journalist was allowed to visit the apprentice school.
Set up by an eccentric musicologist called Tagayasu Den in 1970, the group consisted of Sixties dropouts - peace-loving musicians who wanted to get back to nature. They lived in a cashless commune, turning their backs on the wealth and technology of mainstream Japanese society.
Den's obsession with fitness soon made the drummers more famous for their feats of physical endurance than for their playing. They turned up at the Boston Marathon in 1975, for example, and completed the course in professional time, before setting up their drums at the finishing line and playing a two-hour concert. Today, life at the commune in Ogi is more relaxed, but the apprentice school remains as strict as ever.
This year's intake started their first day at the school on 1 April. For the next 12 months they will be living an absurdly ascetic lifestyle: rising at 5.30am, running 10 kilometres (six miles) before breakfast, cleaning floors with ice-cold water (there is no hot water) and drumming for eight hours every day. One candidate might make the grade and be admitted into the esteemed ranks of Kodo. Most will give up after a few months.
After the morning practice in the gym, I found one apprentice, Kiyoshi, resting in his room. The room is cold and contains a futon, two tatami mats that barely cover the hardwood floor, and one or two of his personal belongings. 'It's very difficult adjusting to this lifestyle. I am not in the habit of getting up at 5.30am and running 10 kilometres by 6am. We also spend a large portion of the day barefoot.'
Kiyoshi's daily routine is made even harder by his background. He does not speak Japanese fluently and understands little that is said to him. He was born 22 years ago in Canada and studied economics at the University of Toronto.
'I am 'Nike Sanse', a third-generation Japanese Canadian. My grandparents were born in Japan and emigrated to Canada quite a while ago. Because I look Japanese and have a Japanese name, other apprentices think I understand more than I do. So each day is mentally draining as well as physically exhausting.'
Despite such hardships, Kiyoshi is still smiling. The opportunity to retrace his roots and soak himself in one of the most traditional forms of Japanese culture clearly makes up for everything. He is also enjoying the chance to speak English. It has been a few weeks since anyone has called him Gary, his Canadian name.
He shows me the carpentry room where, on their first day, everyone had to make their drumsticks. 'Before we could even touch a drum, we had to make our own batchi.' In the meal hall four apprentices are lying asleep on the floor around a kerosene heater. The 30-minute break between practice and lunch is sacred.
Apprentices have to be between 18 and 25 years old. Yasuhiko, the eldest at 25, worked for a bank in Osaka for three years before trying to join Kodo. Naoya, 23, has just graduated from Meiji University in Tokyo and Kiyotake, 23, was working in the computer department of a bookstore. Although Kodo does not require its apprentices to have a musical background, these three all played drums for college rock and jazz bands.
The three female apprentices are the source of much discussion. Anyone who has seen a Kodo concert remembers the immensely physical nature of the drumming: fierce arm and body movements rather than delicate wrist technique. The skimpy loincloths seem only to confirm the high levels of testosterone required to be a Kodo drummer. So why are three women applying?
According to Yuka, one of the 15 female members of Kodo's 40 staff, Kodo has always had an enlightened attitude to women, compared with the rest of Japan. Women are, however, employed in every capacity except drumming and she doubts that women will ever share the same stage as Kodo's men. 'There are so many women playing the drums in Japan. Female drummers don't have to drum hard and they don't have to be cute or delicate. There are other forms of expression. In Kodo, however, the physical style of the drumming makes it difficult for women to keep up.'
Ayako, an 18-year-old high school graduate from Tokyo, hopes to prove her wrong. Unlike the other two female apprentices, she has set her sights on becoming the first woman drummer in Kodo.
Lunch in the warm meal hall is a surprisingly jolly affair. In an effort to become ambidextrous, no one is allowed to use chopsticks with their good hand. Lots of food (egg, bacon, seaweed and boiled rice, washed down with miso soup) is spilt and there is much laughter.
Overlooking proceedings is one of Kodo's founder members, Oi, who in his heyday used to beat the o-daiko, the biggest drum of all. He is now in charge of nurturing young talent. 'It is good for the mind to get the fresh air and briskness of the morning. They must also develop a good body, a style of drumming and an ability not to hurt themselves.'
The meal over, Gary is looking out of the window at the blossom, which has just arrived on Sado. 'If this is spring,' he says, 'I am not looking forward to winter. A few years ago, an apprentice woke up one morning with snow on his face. He decided to pitch a tent in his room and slept in that.'
Kodo is playing at Sadler's Wells Theatre, London, 5-15 May (071-278 8916).
Danny Danziger is on holiday.