Children are not safe in Japan. A thousand cunning creatures, from robots and smiling kittens to duelling, animated stag beetles, are vying to drag the vulnerable into their commercial clutches. The monsters that got my children are called Pokémon. Doe-eyed creatures that come in an assortment of primary colours, they lure the unknowing with helium-balloon voices, cuteness and special fighting powers.

Pikachu, their ringleader, a bright yellow fellow who resembles a demented bunny (go on, sue me), made a play for my kids when we lived in England. Then, they were smart enough to blank out his slick charms. But when we moved to Japan, Pikachu's incessant babbling grew louder and they crumbled.

For some time now, I have observed my kids outside our house, furiously trading Pokémon with a gaggle of neighbours. Sometimes the transaction is made electronically. One Pokémon monster briefly flashes on a screen before miraculously appearing on a pal's hand-held device.

The kids communicate in neither English nor Japanese. They converse in Pokémonese - all "special attacks", "super-effectives" and "HP", an abbreviation (my sources tell me) for a central concept known as "hit points".

I have been more mystified still at the disappearing tricks these monsters perform. It works like this. You enter a multi-floored emporium called Kiddyland. Your offspring scamper up with a razor-thin pack of cards much like all the other razor-thin packs of cards strewn about your home. Then, as if by magic, $10 vanishes from your wallet.

Imagine my horror, then, to discover these nasty creatures had set up camp in Nagoya, west of Tokyo. What could we do but go?

One Friday morning, we awoke my sleepy children and told them they were skipping school that morning. (If Mr Jeffrey is reading this, the reason - as I explained in my note - is that they had very high temperatures, although I may not have made it clear that symptoms came on shortly after we told them they were going to Poképark.)

The pilgrimage began with a bullet-train ride. Even for an adult, it is a thrill to board the shinkansen, a white eel of a train that slithers silently along its tracks, devouring distance.

A short taxi-ride from Nagoya station brought us to the hallowed gates of Poképark. We were greeted by a furry creature of unknown identity (at least to me), who proceeded to paw at my children in the 95°F heat. Then, after filling up on Edy money (nothing so mundane as yen in Poképark) we joined the human hoards.

Our first stop, as visits to these sorts of places demand, was a frighteningly long line leading to a far-off destination of dubious interest. It emerged we were queuing for Rayquaza (twister attack), a friendly, bright green dragon who doubled as a roller coaster. My kids could not believe their luck.

The queue inched along but the waiting children didn't seem to mind. Most were absorbed by Pokémon games, electronic or otherwise, or stood dumbfounded as a cavalcade of cartoon creatures plied them with safety instructions. (Airlines, take note.)

At least most of the people around were children. In Tokyo Disneyland, a place I will forever associate with a thundering migraine, the bulk of visitors seemed to be adults. I remember being about to board a Peter Pan ride with my children, only to be elbowed aside by a lone woman in her sixties, who sailed off to Neverland in her gondola like some modern-day witch.

At Poképark, all the familiar monsters had mustered. We joined Mudkip (tail strike) for a ride that ended in an unsolicited shower, and took a turn on Raikou (thunder bolt), who turned out to be a merry-go-round. Then we sailed above the Pikachu forest.

After each ride, we were presented with a card bearing a picture of one of the monsters, wrapped in cellophane to preserve its pristine preciousness. I received my very first - Rayquaza, HP 80, dragon attack 40.

My own HP was running low in the blazing heat, so we took a break. Food stalls were offering typical Japanese fare. There was yakisoba noodles, yakitori chicken, inarizushi tofu-covered rice cakes, and takoyaki minced octopus balls. The heaps of takoyaki piled on one stall inevitably provoked the wide-eyed question: "How many balls does an octopus have, then?"

HP restored, we clambered aboard the ferris wheel. Sat in our little glass world, a Pokémon song crackling through dysfunctional speakers, we slowly ascended. There was the park, with all its gory colours and spinning machinery.

As we rose, we looked beyond to the mundane world of adults. A bullet train sped into Nagoya station. The prime minister of Japan suddenly appeared on a building-sized TV screen. Pachinko parlours, gambling dens for people with a yearning to trade wages for silver balls, pulsed with lights. Outside, cartoon characters held up slogans spelling out the virtues of pouring one's money down the toilet. One read: "Let's play Daitokai and be happy."

This was the world of adults. No wonder my kids found sanctuary in monsters.

Poképark, Sasashima Cargo Station, Nagoya, Japan; www.pokepark.jp