We've had cocktails in Vampire Cafe, which had a tacky Phantom of the Opera-esque vibe. And we've had shots of sake in establishments themed on movies, prisons and hospitals.

Now we're off to Kagaya, which we've heard is "the best - and maddest - bar in Tokyo".

It's hidden in the old Shinbashi district south of Ginza, but when we find it, we're a little perplexed. Compared to the other bars - not least Alice - Kagaya looks a bit bland; ostensibly a tiny basement apartment, with a kitchen fronting on to a wood-floored lounge.

We consider U-turning, but we're urged to sling off our shoes and make ourselves at home by the bar's only patrons - six besuited Japanese businessmen sitting cross-legged at a low table.

A few seconds later, an apparently normal, self-effacing man in his 40s appears. In front of him, a remote-controlled anime-inspired Anpanman robot suddenly jerks forward, carrying a couple of steaming hot face towels.

Behind it, the man starts leaping up and down, making a series of bizarre noises. Then, in a strange robotic voice, he welcomes us, says his name is Mark Kagaya and urges us to take the towels.

Kevin and I look at each other in bewilderment. The Japanese businessmen are rolling around in hysterics.

"It's your first time here?" asks one. We nod. He admits that Kagaya is his regular and that he always brings new work-mates here for shock value.

This was once a traditional izakaya (tavern), run by Kagaya's parents. Then Mark took over and decided to improvise, eventually transforming it into his idiosyncratic theme bar.

Punters can order beer, whisky and sake, plus a selection of home-made dishes like grilled fish, fried chicken and miso soup. Then they wait for Kagaya to entertain them.

His party trick is to deliver the refreshments in a theme associated with a country of the customer's choice. He gives us a few options. We skip the obvious (Japan) and pick a random (France).

Kagaya soon reappears in a beret and striped jumper, carrying a canvas and brush, his body full of faux French mannerisms as he proceeds to portrait-paint Kevin, while muttering French phrases to himself. His somewhat crudely stereotypical behaviour is so utterly bizarre, we can't help giggling.

Kagaya presents his (impressive) illustration of Kevin with two mugs of beer. When we pick them up, the businessmen start guffawing again.

The mugs are battery-powered and vibrate when we try to drink from them. The jovial businessmen head off, on slightly unsure footing, soon after. Later, a group of Asian-American tourists arrive. They, too, have heard about Kagaya on the grapevine.

We consider hanging around to see what pranks he has in store for them, but we decide one surreal and unpredictable hour is enough. Our bill arrives in the mouth of a Barbie doll, via the remote-controlled robot. We pay and leave a tip, but Kagaya refuses to take it.

"In Japan you don't tip," he says, in a normal voice.

But we insist. He smiles and bows. "OK," he croaks, in his robotic voice. "Come again."