Remember when you were little and the days were long and filled with play? Back then, too, your playmates likely included a happy band of figures and stuffed animals that took on lives of their own in your imaginary world.

Tomohiro Yasui spent just such a childhood in the old castle city of Hikone, on the shores of Lake Biwa in Shiga Prefecture.

Unlike all those familiar mass-produced Mickey Mouses, Licca-chans or R2-D2s, though, he made his playthings himself. But cuddly creations they were not, because the young Yasui's flights of fancy were paper robots about 15 cm high that were, in his vivid imaginings, pro wrestlers as fierce as they come.

Using old boxes and bits of wire as his raw materials, Yasui formed his own stable of about 20 fighters with different faces, costumes and names. They were creations partly inspired by a popular early 1980s robot animation called "Mobile Suit Gundam." Holding one in each hand, he would spend hours making them wrestle in a ring he made from a cookie box in a world of his own.

Many kids come up with their own games, but what makes Yasui remarkable is that now, at age 33, he is still playing with his robot warriors.

While most people forsake such childhood pastimes in their teens, this present-day Kyoto resident has never abandoned his toys and has continued to entertain himself with them in secret.

Over the years, the games he play have turned into an elaborate spectacle he calls "Kami-Robo Wrestling." More than 200 wrestlers live in this world, and between them all there are long and complex histories of enmity, friendship, victory and defeat.

Reset from a busy day

"I've always thought this wasn't right, you know, for an adult my age to be playing with robots and making them fight," said Yasui, a bit shyly -- but with a cheerfulness typical of Kansai people, and not at all like a nerdy otaku.

"But I guess for me," he continued, "it's something similar to taking a walk or having drinks at night. It's not a necessity, but when I play with them, it helps me reset myself from a busy day."

Today, a typical Kami-Robo Wrestling bout takes place in the evening when Yasui is at home relaxing with a drink. Getting the wrestlers out of the boxes they are carefully stored in according to the "organizations" they belong to, Yasui decides on the bouts for the night's pugilistic extravaganza. "I try to think who would attract the biggest audience," he says.

Each fighter has his own signature move, like a chop, twist or kick, and their characters often reflect one of Yasui's own traits: Some are weak, while others are vain, spiteful, passionate -- and even lackadaisical. These and other considerations such as past results and relations between individuals and organizations all influence the match and the drama of the bouts, he explained.

As puppetmaster, Yasui can hardly avoid having some preconceived image of a bout when the starting bell rings. But he also strives to make it more exciting and take on a life of its own. "During a match I keep questioning myself: 'Are they really going to finish according to my prediction?' " he said. "Then, at the point when the match seems to be about to come to an end, a surprise counterattack often occurs -- and that's when the game starts developing by itself, and I really get unexpected results."

During each heated bout, as his characters bob and weave and lunge and leap almost in a blur in his hands, Yasui explained how he enjoys switching his mind around to "watch" the contest from many points of view -- sometimes that of a spectator, other times that of a young wrestler gleaning tips from the ringside, or perhaps as a promoter coming along to see if everyone is having a good time. Oh, and when a wrestler gets injured, Yasui becomes the "doc" and fixes their problems.

With a private world like this and his job as a plastic-arts designer/creator of little giveaways attached to boxes of candies, it seems somehow that Yasui just has to be the kind of obsessive, otaku-type geek the media never tire of featuring. But he's anything but, and clearly that first impression of his easygoing Kansai nature really is not misleading -- with humor never more than a few moments away. "I think it was not because of any talent, but my desire to make people laugh that made me creative as a kid," is how he puts it himself.

During this interview held at Tokyo's Parco Museum in Shibuya, where his "Kami-Robo Expo 2005" was staged last month, Yasui repeatedly expressed his embarrassment about his secret pastime going public.

Courage summoned

"I still can't feel proud of all this, but I recently decided not to try to disguise my embarrassment when I speak so that people can understand it more accurately," he said.

In fact Yasui first came out about his Kami-Robo world a few years ago, when he summoned the courage to reveal his passion to Katsunori Aoki, a well-known advertising art director he had enjoyed working with. To Yasui's relief, Aoki was very impressed with his creativity -- so much so that he encouraged him to go public.

At the Tokyo exhibition, which attracted crowds of all ages, several boys brought their own paper robots along to show to Yasui and get him to autograph the show's catalog. Among them were some 10-year-olds, prompting Yasui to comment in characteristic style: "I'm surprised to realize that I was that young when I started -- but you know, I still can't believe I'm signing autographs because of this . . . "