We Brits may think we like our food fresh, but it's nothing compared to the Japanese.

When I lived in Japan in the mid-90s, I heard of the delicacy involving fish sloshed and stunned in sake and eaten live - but even I found some of the culinary habits on display in Fish! A Japanese Obsession (9pm, 23 March, BBC4) hard to stomach.

Whereas many of us baulk at the mere sight of a whole fish on our plate, our south east Asian cousins think nothing of going to a restaurant, catching the fish they fancy and waiting patiently for the chef to carve it into sashimi before serving it up alongside the still-quivering head and flesh-free skeleton. Not only do the Japanese have no conflict with eating what was once alive - they don't care if it's still alive or, for that matter, if it's endangered. And the programme's earnest presenter, Charles Rangeley-Wilson, tried, but failed, not to pass judgement.

As with any good horror film - and this bore all the hallmarks of the genre - it was the scenes that initially looked innocent that were most shocking.

At one point, Wilson's enigmatic guide, Aki, has live prawns delivered to the hotel room.

"The prawn is crying," he says coolly, holding one aloft in a manner reminiscent of Robert De Niro in his famous egg-peeling scene in Angel Heart, as Wilson looks on aghast.

The sight of bluefin tuna strewn across the floor in Tokyo's answer to Billingsgate Market and people queuing up to eat barbecued whale meat (apparently it tastes like beef, not chicken) is no less unsettling.

There was light relief too. One of the funniest characters I've seen on TV for ages was the mad bloke whose mother makes funazushi, a putrid looking (and apparently tasting) fermented raw fish dish.

After repeatedly trying to hijack the filming, he persuades the hapless presenter and his guide to don tiger and panda suits, and one (the panda) to take to the skies while the tiger waves at him from the ground. Quite what that had to do with his fish business, who knows.

But as a bemused Wilson concludes at the end: the window on Japanese culture has a curtain that's hard to pull back. And fish is just for starters.