NAGASAKI - The large framed color photograph shows stark reality.

The boy in the photo is lying face-down, apparently dead. His back, from neck to waist, resembles raw meat.

Today, that boy is Nagasaki's leading nuclear disarmament champion.

Sumiteru Taniguchi, now 66, was the most critically injured person to survive the atomic blast 50 years ago over this city.

Taniguchi holds a record he wishes he did not: He was hospitalized for three years and seven months - longer than any other person injured by the detonation.

He was 16 years old that summer day and was scheduled to have that Thursday morning off from his job at the telegraph office. But he had been called to work.

As Taniguchi set off on his bicycle to deliver wire messages, an air raid siren broke the morning quiet.

"I thought about going to a shelter, but soon the siren stopped. I kept pedaling. Odd that I remember the sky was clear."

In the next instant, he was catapulted - bicycle and all - a dozen feet and slapped against the road by a blast the color of rainbows.

"The ground seemed to quake and I clung to it for dear life."

When he raised his head, buildings were in ruin "and bodies of children who had been playing at the roadside were scattered around me like clumps of garbage.

"I thought I, too, was on the verge of death. But I spurred myself to stay alive."

Minutes passed, perhaps an hour. Finally, Taniguchi stood up. As he did, skin hung down from his left shoulder to fingertips.

"I touched my back with my other hand, and when I took it away, something like black grease stuck to my fingers."

He looked around for his telegraph pouch and stumbled off, glancing back at his prized bike, now twisted steel.

Nearby buildings were in flames and fires were breaking out on surrounding hillsides.

"People who had survived were squirming in pain on the ground. Their hair was gone, their faces puffed up."

He thought he was one of the lucky ones.

"I felt no pain and had no bleeding whatsoever. But I trudged along like a sleepwalker to an arms factory that had operated in a tunnel and sat down with others.

"The tunnel was full of injured people, but for some reason the horror of the situation did not register on my mind.

"I asked a woman in the tunnel to cut off the skin flapping around my arms. After doing so, she rubbed machine oil over the burns with the remains of my shirt."

Those huddled in the tunnel feared another attack. "We had to leave, but I no longer had the strength to stand up."

A man put Taniguchi on his back and carried him to a nearby hillside. Darkness came, the night sky lit by fires raging below.

"From time to time, enemy aircraft roared overhead, spraying the ground with fire."

Rain began to fall and he quenched his thirst by licking water from leaves.

When dawn broke, not one person around Taniguchi remained alive. Day came, and a medical crew came to the hillside. But Taniguchi was too weak to call out and no one saw him blink his eyes. They left him for dead.

The next afternoon, rescuers found him. By then, blood was dripping from his back and he was in intense pain.

They carried him off the hill on a blanket to a temporary hospital, where for the next month his burns were treated with a mixture of oil and paper ashes.

In September, he was transferred to the Omura Navy Hospital. His strength ebbed, his burns ran with pus and filled with maggots.

He lay face-down for the next 21 months, "crying out for someone to kill me.

"No one expected me to survive. On their rounds every morning, doctors and nurses whispered to each other, 'He's still alive.' "

At home, his parents, who escaped injury, planned his funeral.

For, in addition to the burns, lying face down caused massive bedsores to form on his chest.

"Holes opened between my ribs and the movement of my heart and other organs became visible through the skin."

In January 1946, U.S. Marine photographer Joe O'Donnell snapped Taniguchi's picture while recording war damage in 50 Japanese cities. The two men met when O'Donnell returned to Nagasaki in 1993.

At that time, O'Donnell took another picture of Taniguichi's back. The photo, which shows tumors growing in the scars, will be exhibited at the Atomic Bomb Museum this month as Nagasaki commemorates the 50th anniversary of the end of what the Japanese call the "Pacific Ocean War."

Ramrod straight with quiet dignity, Taniguchi captures visitors' attention during the formal and traditional exchange of business cards.

His card, which identifies him as president of the Atomic Bomb Sufferers' Council, carries a picture of that lad with the bloodied back.