NAGASAKI - Tsukasa Uchida treasures his box filled with small pieces of burned roof tile.

The tiles tell a vivid tale of personal tragedy Uchida relives today.

The morning of Aug. 9, 1945, tiny amounts of sake and soy sauce were being rationed out in Nagasaki. Housewives formed lines early to wait for the meager handouts.

Suddenly, a ferocious wave of heat from the sky engulfed them. The atomic bomb's fireball vaporized most of those standing at the Fukahori food distribution station, less than a half-mile from the blast's center.

Uchida, now 65, was working that morning at the "top secret" Ohasi branch of the Mitsubushi Arms Factory, about a mile from the blast's center. He daydreamed of how his mother would use the extra soy sauce to add spice to the daily evening meal of pumpkin gruel.

It was nearly lunch time and Uchida's friend also was thinking of food. "Let's eat early," he urged.

Uchida waved him away, planning to eat after he finished the torpedo assembly task he had been assigned.

"Without any warning, a bluish flash of light and fierce shock wave descended. Roof slates crumbled, thick translucent glass panels shattered, and just as I glimpsed the blue sky, a shower of glass splinters rained down unmercifully like gunfire."

His skull cracked when he was smashed on the head with broken glass and iron framing.

"I remember wringing blood out with my headband to try to stop the bleeding. Then I covered my ears with my thumbs and my eyes with my fingers and fainted."

When he came to, he saw twisted pieces of iron hanging from the ceiling and nearby the body of a co-worker.

He crawled out of the ruins and was helped to a nearby hillside.

"There was a soft growth of mugwort that had escaped the heat, and I used it as a pad for my wound to stop the bleeding." The plant is believed to have healing power.

Uchida staggered down the hill, crossed a small stream and looked from the railroad tracks toward Urakami Station.

"The entire area looked as though it had been run over by a steamroller - the only thing standing was the chimney of the Mitsubushi Iron Works. I walked aimlessly down the tracks. The heat was unbelievable."

Uchida wandered numb that day, stepping over bodies, trying to block out the cries he heard around him.

Starless night settled on the burning town. A relief train arrived, its whistle blaring through deadly silence.

Uchida struggled onto that train, where he found the friend who had asked him to take an early lunch. "My friend's face and body were scorched black, and apparently he was blind because he didn't respond until he heard my voice.

"He touched my body, which was sticky with clotted blood, and encouraged me saying, 'Don't die.'

"He asked me about his own injuries. For his sake, I touched his shoulder and replied, 'They're light. Don't worry.' But when I removed my hand, the skin on his shoulder stuck to it and ripped off. I was mortified."

Before the bombing, Uchida heard an explanation about the structure of the atom and nuclear fission from a chemistry teacher. Remembering that lesson, he told his friend, "Only an atom bomb could cause this kind of destruction.

"My friend didn't hear me. He had already drawn his last breath."

The next morning, the train arrived in Omura, some 12 miles from Nagasaki. Uchida was carried on a stretcher to a nearby naval hospital.

"I remember later the sound of beds being rolled out into the corridors, and lamented over the fact that other injured people were cured so quickly and I was left in the hospital."

"Why?" I asked.

"All others are dead," a nurse whispered.

Uchida looked under the lightweight blanket on his bed and saw scattered on the sheet splinters of glass, which had stuck out of him as though he were a pin cushion.

A week later, he was released from the hospital, not because he was healed, but because someone else needed his bed.

He took the train back to Nagasaki and walked toward his neighborhood in Matsuyama-machi, the heart of the district destroyed by the atom bomb.

Suddenly, there was a frail and dazed elderly woman walking toward him.

"It was my mother. We both thought we were dreaming."

Uchida was wrong about his mother. She did stood in line for sake and soy sauce that morning. Instead, she was scouring the countryside for vegetables.

"My mother embraced me hysterically and wept tears of joy. She told me she had searched around all makeshift hospitals, but she could not find me."

They walked arm-in-arm to their home in Ohaski-machi, almost directly at Ground Zero.

Not a living being was in sight. Not a house remained standing.

The main road had been cleared in the week since the bombing, but bodies remained in the wreckage.

"We saw six skulls lined up on the barren ground staring up at the sky, with no other traces of human bones in sight."

Uchida found the charred body of his father. And he dug through debris, tossing aside bits of roof tile, looking for traces of his two younger brothers, sister and aunt.

"I dug at the earth with pieces of scrap metal and broken dishes, and found something that appeared to be a fragment of human bone. The consistency of it was like a small pile of fine tissue papers. When I touched a stick to it lightly, it crumbled and was swept away by a passing gust of wind.

"Suddenly, it was gone and a crushing feeling of desolation overcame me. I felt a great rush of anger well up inside me. How could something so absolutely ridiculous happen?"

His youngest brother had begged their father to evacuate the family after an air raid a week before the bombing.

"My father rebuked him and called him unpatriotic. It grieves me to no end that my father went on believing in the immortality of the Japanese empire, and because of it my family had to die."

Uchida and his mother eked out a living in post-war Nagasaki by pushing carts of vegetables from farms into the city to sell on street corners.

By the summer of 1946, makeshift huts dotted Matsuyama-machi - primitive, unsanitary structures that often housed several families. "We built a house on our same property."

One day, an old woman appeared at their doorstep with a mat and asked if she could sleep on the earthen floor. She gathered charcoal from the ruins and brought it into the house to make a fire.

"I was astonished to find among it charred fragments of human bones. We were literally living in a graveyard. The price that was paid for the peace we now enjoy must never be forgotten."

For Uchida, the reminders are those tiny pieces of roof tile from the wreckage of his home.