Nobusuma

Something soft and furred and winged comes out of the dark and slaps flat over your face.

You can't see. You can't shout. It's warm and it's alive and it's covering your mouth.

And while it's there it takes something — a sip of blood, or the oil from your lamp — and then it's gone into the trees, and you're standing on a road in the dark with your heart going.

That's the nobusuma. The name means roughly "field bedding" — the blanket that attacks you.

It's a flying squirrel

That's the kernel, and it's a good one, because the real animal genuinely does this.

The musasabi, the Japanese giant flying squirrel, is about the size of a cat, and it glides — launching off a trunk, spreading a membrane between its limbs, and sailing thirty or forty metres through the canopy in silence.

They come down onto things. In the dark. Without a sound. Something the size of a cat, with a skin membrane, arriving at head height out of nowhere.

You don't need to invent much from there.

Sekien's 1779 caption is essentially doing zoology: "a giant flying squirrel" that "resembles a bat, with fur, equipped with fleshy wings."

A monster catalogue doing comparative anatomy on a folk terror.

What it's after

The record has a list, and the list is a nice mix of the frightening and the mundane.

Blood, sipped. Lamp oil, stolen. Nuts, eaten.

And — my favourite — the flame-tips of torches.

It comes out of the dark and bites the fire off the end of your light.

The career path is the real story

Here's what makes this entry unusual, because the Edo sources give the nobusuma something almost nothing else in the tradition gets: a documented promotion track.

Per the 1841 picture-book:

An aging bat becomes a nobusuma.

An aged nobusuma becomes a yamachichi — the "mountain father."

And the yamachichi is a serious escalation. It creeps up on people while they sleep and sucks the breath out of their mouths, which kills them.

Unless — and this is the strangest mechanic in the whole ladder — a second person witnesses it happening. If someone sees the yamachichi at work, the victim doesn't die. Their life is extended.

The same act kills you unobserved and lengthens your life if watched.

Nobody has ever explained that to my satisfaction, and I've decided I like it better unexplained.

There's a fourth rung too, catalogued separately: the aged flying squirrel that becomes the momonjii, the old man at the crossroads whose company makes you ill.

Aging doesn't finish these creatures. It promotes them.

That's the principle, and once you have it you see it everywhere in this tradition.

A cat kept too long grows a forked tail and starts commanding corpses. A fox accumulates tails, one per century, until it has nine and can see the whole world. Household objects reach a hundred years and stand up and walk.

Age is not decline here. Age is accumulation — of power, of grievance, of whatever it is these things are storing.

But the bat-to-nobusuma-to-yamachichi chain is the only one written down as an explicit, ordered sequence with each stage named and illustrated.

Somebody sat down and drew the whole life cycle of a monster, across two catalogues, sixty years apart.

One warning about the name

Kōchi Prefecture has its own nobusuma, and it is a completely different creature.

Written with different characters — 野襖, "field sliding-door" — and it's a wall. An invisible obstruction that blocks the road and won't let you past, in the same family as the famous wall-yokai.

Same sound. Different kanji. Unrelated monster.

Which is a hazard worth knowing about generally. In a tradition transmitted largely by ear, across provinces that couldn't read each other's dialects, two things sounding alike is not evidence of anything at all.