血洗島

'Blood-Washing Island.' A mountain god washed his severed arm here, says the legend. The likelier culprit: the Tone river, whose floods washed the land — 'chi-arai'. The blood is probably a typo. The scariest names often have the dullest origins.

No settled theory, says the city itself. A wounded mountain god washed his severed arm here, goes the legend Shibusawa Eiichi himself liked to retell. Or a samurai's arm, severed in battle. Or an Ainu word wearing scary kanji — one account glosses it as shore, far end and the like; another as the lower outskirts. The city's preferred answer is duller and wetter: the Tone river's endless floods 'washed the land' — chi-arai, land-washing — and the character for 'land' drifted into 'blood'. The blood is probably a typo. The 'island' is real: a rise in the floodplain.

One rise ('island') among the old flood islands of the Tone river's south bank. Shibusawa's family home still stands.