A black cloud settles over the roof of the imperial palace every night at around two in the morning, and the young emperor sickens. No physician helps, no prayer helps. The court concludes that this is a matter for an archer, and sends for one.
That is the opening of the most cinematic monster hunt in Japanese literature, and it is told in the Heike Monogatari, a work otherwise concerned with the collapse of a real aristocratic house in a real civil war.
Assembled from four animals
The creature has the head of a monkey, the body of a tanuki, the legs of a tiger and a snake for a tail. Some tellings give it the trunk of a badger or the forelegs of a different beast; the Taiheiki and later versions shuffle the parts. It has no single defining feature — it is a composite, and the composite is the point.
What ties the parts together is the cry. Nue was originally the name of a bird, generally identified as the white's thrush, whose call is a thin, drawn-out, high whistle that carries a long way through night woodland and sounds, to a great many listeners, deeply unpleasant. The monster is named after that sound rather than after its body, and in the oldest usages nue means the bird and the eerie noise, not the chimera at all. The Man'yōshū already uses the bird's name as a poetic epithet for weeping.
That makes the nue an unusual case: a monster generated by a sound, which then acquired an animal composite to explain the sound's strangeness.
Yorimasa, and two arrows
Minamoto no Yorimasa — a real man, a poet of some distinction, and later the aristocrat who raised the standard of revolt against the Taira in 1180 and died at the Byōdō-in — is summoned to deal with it. He takes his retainer Ii no Hayata and waits.
The cloud arrives. Yorimasa cannot see the thing inside it, so he prays, nocks an arrow, and shoots at the cry. Something falls; Hayata is on it before it lands and stabs it repeatedly. The court, examining the body by torchlight, finds the mismatched animal.
The emperor rewards him with a sword named Shishiō, "lion king", and the Heike stages the presentation as a courtly set-piece: the minister handing it over composes half a poem about the cuckoo calling above the clouds, and Yorimasa, kneeling, completes it with a line about a crescent moon and modest merit — a demonstration that the man who shot the monster is a poet first. This is the sequence the Heike actually cares about. The monster is the setup for a couplet.
Yorimasa is later called on a second time, in some versions, to shoot a different night-crying creature, and the sources differ on whether that is a repetition, a doublet, or a separate incident. The Taiheiki preserves further variants.
The body in the boat
What happens to the corpse is the part the tale takes seriously. It is put into a hollowed log or a boat and set adrift on the river, which is the standard Japanese method for disposing of pollution — send it downstream and out to sea, away from the capital.
Local traditions then pick it up. A mound at Ashiya in Hyōgo claims the boat came ashore there. Nue-zuka, a nue mound, stands in Osaka in the Miyakojima area; Kyoto has a related site and a pond associated with the washing of the arrowhead. The Noh play Nue is built on this after-life: the ghost of the creature appears to a travelling priest, describes its own death from the inside, and asks for prayers, having been denied any rest because it was thrown away rather than buried.
That play is the most sympathetic treatment any Japanese monster receives. It gives the thing an interior, a grievance and a request, and it makes Yorimasa's celebrated shot look, from the other end, like a killing followed by an insult.
What a chimera meant to a medieval court
There is a reasonably persuasive political reading. The nue's components — monkey, tanuki, tiger, snake — have been connected to the directional animals of the zodiac and thus to a disorder of the whole cosmological scheme, an emperor's illness expressed as a compass gone wrong. A related line of interpretation takes the creature as a figure for the factional chaos of the late Heian court itself, a body made of incompatible parts, and notes that the Heike gives the episode to Yorimasa specifically, the man who would later try to overturn the settlement and fail.
Both readings are modern and neither is provable. The undisputed part is that the Heike Monogatari's compilers put a monster story into a work of political history and expected it to be read as continuous with the politics.
Persona, Sekiro and the composite silhouette
The nue is a fixture of Japanese games precisely because a chimera is easy to design and hard to confuse with anything else. Persona, Nioh, Onmyōji, Yo-kai Watch, Ōkami and the wider Megami Tensei family each have their own; Sekiro and its neighbours borrow the shape for aerial night-fighting bosses. Fate-adjacent franchises use Yorimasa as a servant with the nue as an attribute.
Anime and manga tend to use it as a name for something composite and ominous rather than reproducing the Heike plot — the word functions as a label for hybridity. Japanese political journalism does the same: a nue-teki politician is one whose positions cannot be pinned down, a usage that would have amused the Heike's compilers.
Is the nue a yōkai or an omen?
An omen first, and the distinction shapes everything about it. It does not eat anyone, haunt anywhere, guard anything or make bargains — it arrives, it produces illness in a specific person, and it is destroyed. That is the behaviour of a mononoke or a portent in the continental tradition of reading disorder in nature as a judgement on a ruler, imported into Japan along with the rest of the Chinese apparatus of state divination. The court's response confirms it: a bureau of diviners is consulted before an archer is. The later yōkai catalogues absorbed it into a general bestiary and gave it a body to be drawn, which is how a portent becomes a monster with a picture. The tengu started the same way, as the name for a noise in the sky.
Why shoot at a cloud rather than at the creature?
Because the Heike is making a specific claim about Yorimasa's skill and about the nature of the threat. The thing is not visible; what is available is a sound and a direction, and hitting a target identified by ear alone is the exact demonstration a Japanese archery tradition would recognise as extraordinary — comparable in the same work to Nasu no Yoichi's shot at a fan on a boat rocking in the swell. It also matters theologically: Yorimasa prays first, to Hachiman among others, and the arrow's flight is presented as sanctioned rather than merely accurate. A hunter who kills what he cannot see has been given permission, which is the Heike's way of saying the court was right to send him.