Yofune-nushi

A sea serpent off the Oki Islands, demanding one girl a year.

Under fifteen. Delivered by ceremony, on a fixed night in mid-June, at a cliff.

And if the village defaults: storms, and drowned fishermen.

The description is unusually precise. About eight metres. White. Scaled along the back. And phosphorescent — glowing "under the deepest of water."

Tokoyo

A young woman called Tokoyo came to Oki looking for her father — Oribe Shima, exiled there by the regent Hōjō Takatoki.

She found the village on the night of the ceremony.

And she took the sacrificial girl's place.

She went to the cliff, as scheduled, in the girl's clothes. And then she went over — with a blade.

What she found in the cave first

This is the part I didn't expect, and it comes from the primary text.

Before the serpent appears, Tokoyo finds — submerged in the cave — a wooden statue of Hōjō Takatoki.

The man who exiled her father. The reason she is on this island at all.

She considers destroying it.

And she decides not to. The line given is:

> Better do good than evil.

She is binding the statue to her back to bring it up when the serpent comes.

And then she kills it

The fight is specified, and it's won by optics, not strength.

She takes the right eye first.

And then drives in from the blind side, to the heart.

She surfaces with the body — and with the statue — and the tribute ends. And in the full version, so does her father's exile.

It's the sacrifice-audit's endgame

There's a whole family of these stories, and Tokoyo completes it.

Elsewhere: a traveller doubts the tribute and exposes the monster. A hunter substitutes himself with dogs. A monk overhears the creature singing about the one dog it fears, and sends for it.

In every case, somebody from outside intervenes on the victim's behalf.

Here, the auditor, the victim, and the champion are the same person.

Tokoyo boards the ceremony as scheduled and converts it into the monster's funeral.

Nobody rescues her. She keeps the appointment and declines the role.

The provenance needs flagging, and then it improved

This story enters the record through Richard Gordon Smith's Ancient Tales and Folk-Lore of Japan (1918) — a Western collection. There's no Japanese-language article, and the native lineage is unverified.

Which normally means treating the whole thing carefully.

Except that the full chapter has since been read, and it's better sourced than the summary suggested — and, crucially, Smith hedges his own material in print.

He dates the story to around 1320, and then says of his informant's geography: "I doubt his geographical statement."

A collector who publishes his own doubts is doing the job properly, and it raises my confidence in everything else he wrote down.

He also notes that only two Europeans had visited Oki — and that one of them was Lafcadio Hearn.

The tradition's two great Western collectors, crossing wakes at the same remote islands.

(The statue, incidentally, was enshrined afterwards at Honsōji in Kamakura.)

And it glows

One last thing, because it's the only one of its kind.

The sea in this tradition is dark. The sea-monk is a black dome against a black sea. The giant ray is mistaken for ground. The drowned rise as shapes.

Yofune-nushi is lit.

A white, luminous, eight-metre serpent, visible under the deepest water — as if the tribute system required its recipient to be seen.