The sun dropped over his shoulder into the western suburbs and the man watched a blaze of neon break out on Tokyo's darkening skyline. "I first came here right after the war and it was disastrous. Back then the Ginza was dark and deserted after 8 at night. I was a student and so hungry. I could only afford bread."

Thirty years later, on a rooftop 10 stories high in the glittering heart of the Ginza, Tokyo's prime entertainment and shopping district, he didn't need to say any more. As the world's most spectacular neon show began to burn, whole buildings rippled and pulsated with all the dazzling hues of the electronic rainbow. Michimasa Sato, 46, studied electrical engineering and went on to build many of the huge signs the Japanese welcome as a symbol of peace and prosperity.

Day and night hung in the balance until a timer current flowed through six miles of neon tubing, and the red and white sign of the "Washington" shoe store put a giant brand on the horizon that you could see from an airplane. "We built this 10 years ago," said Sato, as he strolled a catwalk. "It was hard, dangerous work."

The aging neon has to be renewed. Sato's fellow workers will soon throw the sign another 60 feet into the air on a steel and concrete framework to battle a rival shoeshop's display across the rooftops.

"Traditionally the Japanese have always been fastidious about elaborate designs in cloth and decorations," explained psychology professor Hiroshi Minami. "Once we get started we don't know when to stop and it's that way with neon signs."

The peacock gaudiness of the signs conveys a certain national vanity. To foreign vistors and the Japanese themselves, the neon marvels record Japan's extraordinary economic advance in the post-war era.

In other countries neon is scorned and limited as an environmental scourge. In Japan where it is regarded as a creative mix of art, technology and commerce, it flourishes in garish profusion. There are 20,000 signs in Tokyo alone and nationwide the neon uses enough electricity to light 64 million 100-watt household bulbs. Three hundred companies employing thousands of neon designers and erectors are locked in competition for the next eye-catching hit. There are awards for the winners and credits in a thick neon industry magazine. "We have a maximum of 30 seconds," said designer Hiroyoshi Inchino, "to go through about 12 phases and make beautiful colors."

For prestige reasons, all the famous names in Japanese automotives, electronics, cameras and liquor have their names up in lights. One tire company paid $650,000 for an ornate display on the tourist route into town from Haneda Airport which is hung with some of the best exhibits. Another advertiser will pay $60,000 a year to rent a strategic rooftop in the Ginza.

Noted sculptor Taro Okamoto contrasts the wild use of neon with the normally serious, controlled and conformist nature of the Japanese: "The signs are a symbol of modern Japan. By day the cities are rather boring. At night the neon makes them more fascinating."

Around 5:30 p.m. the business districts empty as the 'salarymen' head for their favorite watering holes in the picturesquely narrow streets of the Ginza. As the armies of secretaries vanish into the subways and head for the suburbs, kimono-clad hostesses totter on gilded heels toward the blinking night-club signs.

The psychological link between neon and enjoyment dates back to the red light quarters of 1615-1867 when Tokyo was known as Edo, according to Minami. "The bright lights always meant amusement or entertainment. They make our night-life longer and more colorful."

Advertising lights were first used in Japan centuries ago when traders hung lanterns to illuminate their wooden shop signs. In the 1920s neon came across the Pacific and lit Tokyo's cafe society.

The lights went out in World War II and stayed that way until 1946 when a bunch of occupying GIs arrived at Goro Takamura's workshop. "They were in a hurry and they wanted a sign for a cabaret which was opening close to Gen. MacArthur's headquarters. I don't remember the name, but the sign was a neon horseshoe," he remembered.

Takamura's Showa Neon Co. employed four people then. Now he has 160 working for him. Last year they designed and installed 5,453 individual neon displays including a 120-foot monster boosting an automaker. "We specialize in big signs," he said with a hearty laugh.

Takamura's signs burn in languages he can't speak and countries he hasn't visited - Saudi Arabia, Mexico and some Southeast Asian nations. The Sato we left on top of the Washington shoe store is one of his trusted lieutenants and was dispatched to Moscow when Aeroflot, the Soviet national airline, needed a neon arrangement.

A supervisor now in an ill-fitting suit. Sato's heart is still up on the rooftops with the erection crews. He drives with one eye scanning the neon and knows he can travel to any town in Japan and see his handiwork. "I always used to think this sign will be perfect," he recalled. "I was never satisfied. I don't think I can make a perfect sign," he said with serious humility. Some he remembers with sadness as sites where five of his men died in falls.

During the oil crisis the Japanese government ordered all neon signs switched off and even now the hours of operation are curtailed by law. Takamura has a shrewd response for people who suggest his neon signs waste money and energy: "Tokyo was all burned down after the war and I don't want it to happen again. While the neon is alight, the world is at peace."