Recently, a few days before my 70th birthday, I was visited by the beautiful and vivacious actress Mayu Tsuruta. If you watch Japanese television, I'm sure you will know her from the many films, dramas and documentaries in which she has appeared.

Rare in a modern young woman, Tsuruta loves the great outdoors — which is just as well, because it pelted with rain the whole time she was visiting our Afan Woodland Trust up here in the Nagano Prefecture hills.

Normally I wouldn't take a guest to traipse through the woods for two days in the rain, but we were making a TV documentary and everybody had their schedules.

The program is the third in a series titled "Afan no Monogatari" (sponsored by Ricoh Company Ltd. and set to be aired on BS Asahi at 8 p.m. on Sept. 18), and part of it consists of me cooking something for my guest. Well, Mayu-san brought me a special gift, so it was decided that this would be the focus of the meal I prepared.

The gift came from the sea off the Shiretoko Peninsula in northern Hokkaido, and it was a type of salmon I'd heard of but never actually seen, handled or tasted. Popularly known in Japan as toki shirazu (which means "not knowing time"), it is apparently one of the most expensive fish in the market.

As befitted its price tag, our specimen was indeed sleek and beautiful, and still gleamed silver even after being frozen. It looked rather like an Atlantic salmon, which of course it wasn't; it was a spring chum, scientific name Oncorhynus keta — or shirazake in Japanese. These toki shirazu fish are caught at sea, and common lore and literature both have it that — supposedly unconscious of or indifferent to the seasons — they just wander the ocean.

Chum or keta, otherwise known as dog or calico salmon, are the least commercially valued salmon in North America, maybe because they are mostly caught as they near rivers ready to spawn. At that point in their life cycles, with death following soon after spawning, you wouldn't recognize them as the same silver fish that are supposed not to know time. They grow blotchy purple streaks near their caudal fins and the males develop enlarged teeth, like a dog, and an elongated snout or kype. Not something you'd like to kiss.

The chum or keta have two large races: North American and Asiatic. The North American race spawns in rivers (those that have not been dammed) from Alaska down through British Columbia to Oregon. The Asiatic chum are found in Korea, Japan, Kamchatka, Chukotka, the Kuril Islands, Sakhalin, Khabarovsk Krai and Primorsky Krai. Chum that are caught before they enter rivers have been a traditional source of salted salmon in Japan.

I have eaten plenty of fresh and smoked chum salmon while in Canada, Alaska and Kamchatka (in the Russian Far East), and although some folk turn their noses up at it, I've always thought it very good — and much better than farmed salmon. This, though, would be my first time to try toki shirazu.

My understanding from scrabbling through the literature before trying to write this article and wow you all with my erudition is that the chum are supposed to spend two to five years at sea, and that toki shirazu are just those that have not started to mature sexually and feel the urge to return to their freshwater birthplaces to spawn, so they haven't developed those purple blotches and ugly faces. (It depends what turns you on I suppose — different strokes for different folks; one man's fish is another man's poisson and all that.)

Whatever, when I cut this salmon open I discovered that its genitals were so small and undeveloped that it was hard to tell if it was male or female. As for its age, I kept the head to cook separately, and if I manage to salvage the otoliths (small white bones in the ears of fish) I might slip them under my microscope and count the growth rings.

One half of the fish I sliced away as sashimi. It was excellent, just enough oil content, and a rich orange color. The other half I pinned to a cedar board with wooden pegs cut from a small oak branch from a tree in my garden. Due to the rain, we used the covered balcony of my friend's lodge, where we set up a fireplace with firebricks.

Propping the board and half-salmon at the right angle by the fire, I kept dousing the fish with butter as it cooked. This is a technique I picked up in Finland, and I recommend it as a way of serving large fish; you can turn the board whichever way you want and alter the angle and closeness to the fire to adjust for heat. Burn only charcoal or hardwoods, and with hardwoods you get a nice smoky flavor.

I served the salmon with new potatoes, boiled in their jackets and then doused before eating with hot melted butter into which a handful of freshly chopped basil leaves had been tossed. Good sea salt and black pepper to taste. Mayu-san said she would come back, so it couldn't have been that bad — despite the rain.