Amemasu (also Ō-amemasu, “rain trout”)

The water of Lake Mashū goes black past a certain depth, and the fishermen who kept the old stories did not row out over that blackness without a reason. Somewhere beneath the cold surface lay a fish the size of a whale, pale spots scattered down its flanks, its mouth wide enough to take a boat whole. For most of the year it did nothing at all. It held the lake the way held breath holds a room, and the people on the shore salted their catch and mended their nets and tried not to think too hard about what lay under the keel.

Amemasu is a name the living fish carries too. The white-spotted char swims the cold streams of Hokkaido and the far north of Honshu, a prized catch, common as rain. The creature of the lakes is that same fish grown past all reason. The largest were said to reach from one end of a lake to the other, head against a northern shore and tail trailing off into a southern river. One lay like that in Lake Shikotsu, filling the whole basin. Another rested in Lake Kussharo with its head turned to stone as an outcrop of rock while its tail stretched the length of the Kushiro River. Size is the whole of its menace. It needs no teeth, no fire. It only needs to move.

The Ainu of Hokkaido held that the great amemasu carried the world on its back. The land sat on the fish, and when the fish tired and shifted its weight, the ground above shook and split. This is the same work the giant catfish Namazu does elsewhere in Japan, and the reasoning runs the same way: something huge and alive lies under everything, and its small discomforts are our catastrophes. An earthquake was not chaos. It was a fish turning over in its sleep.

In the older tellings these lake monsters were not only hazards. They were the keepers of their waters, divine in their fashion, owed respect rather than the harpoon. A lake with an amemasu in it was a lake that belonged to something. On a windless morning the surface would lie flat and unbroken, the keeper resting somewhere far below it, and a sensible person fished the shallows along the edge and was home before dark.

The danger wore two shapes. One was the open mouth in the deep. The other walked out onto dry land. An amemasu could fold itself into human form, almost always a young and lovely woman, and go looking for young men. In Minabe, in Wakayama far to the south, a deep pond grew a sudden whirlpool, and each spring a woman rose out of it. For two or three days she would find young men and lead them off. Where she took them no one ever discovered, because not one of them returned. There was a single way to know her for what she was. Her skin was cold, and faintly wet, and clammy as a fish lifted from the river.

That same pond was the end of her. A cormorant dropped into the water to hunt, and the amemasu swallowed it whole, the lazy reflex of a thing that eats whatever fits in its mouth. A little while later her vast body floated up dead, and the bird tore its way out of her belly and back into the air. The villagers raised a shrine to Konpira on the spot, and the shrine is said to stand there still.

Hokkaido tells a harder version. The hero Otashitonkuru went after the amemasu of Lake Kussharo with a harpoon and the flat intention of putting out its eyes. The fish fought him. It pulled, and he would not release the line, and to keep from being dragged under he locked his grip on a rock. The amemasu hauled against him so hard that the rock tore free of the lakebed, and that rock is the island sitting at the center of the lake to this day.

The most ruinous story needs no hero in it at all. An amemasu swallowed a deer that had come down to the shallows to drink, and the deer’s antlers snagged and ripped the fish open from the inside, killing it. Its body was so large that it dammed the lake. A god in the shape of a bird flew to the villages with the warning. Upstream, the people believed it and climbed to higher ground. Downstream, the people did not, and they found the great carcass and dragged it from the water to see what it was, and the lake came after it. Everything below was washed away. The flat Konsengen’ya plain is what the flood left when it had finished.

Its powers are all a question of scale. It can sink any boat, swallow any single creature, lift the earth and let it fall, and pass unnoticed on two legs through a crowded village. Against most of this there is no defense, because most of it is simply weather with a spine. You do not fight an earthquake. But the giant is not invulnerable, and the tales are strangely agreed on how it dies. It dies from the inside. A swallowed bird, a swallowed deer, some small thing taken in carelessly and still able to tear. For all its size the amemasu eats faster than it thinks, and the meal it cannot manage is the one that finishes it. The cold clammy skin gives the woman away. The bottomless appetite undoes the fish.

Frequently Asked Questions

What is the Amemasu?

The Amemasu is a giant fish creature from Ainu and Japanese folklore, named after the real white-spotted char of northern Japan. In legend it grows to monstrous size, sometimes large enough to fill an entire lake, and lives in the deep waters of Hokkaido and the far north of Honshu. The largest specimens were regarded by the Ainu as the guardian spirits of their lakes.

Why does the Amemasu cause earthquakes?

The Ainu of Hokkaido believed a great Amemasu held up the earth on its back. When the fish grew tired and shifted its weight, the ground above it shook and cracked, producing earthquakes. This makes the Amemasu the northern counterpart of the giant catfish Namazu, who plays the same earth-shaking role in the rest of Japan.

How can you tell an Amemasu disguised as a woman?

An Amemasu can take human form, usually that of a beautiful young woman, to lure young men away to their deaths. The one reliable way to recognize it is by touch: its skin stays cold, damp, and clammy like the skin of a fish, no matter how human it appears. In the tale from Minabe in Wakayama, a woman who rose each spring from a pond was eventually exposed and killed this way.

How is the Amemasu killed?

Despite its enormous size, the Amemasu is repeatedly destroyed from within. In one tale it swallows a deer whose antlers tear open its belly; in another it swallows a cormorant that bursts out of its stomach, leaving the fish dead. Its uncontrollable appetite, more than any weapon, is its fatal weakness. The hero Otashitonkuru also fought one with a harpoon on Lake Kussharo, an act that left an island in the middle of the lake.

Related Entries

Akkorokamui, Kamuy, Ainu Mythology, Iwana-bōzu, Namazu, Isonade, Ikuchi, Bake-kujira, Umibōzu, Funayūrei, Mizuchi, Nure-onna, Ningyo, Sedna, Qalupalik