The 雷獣 (raijū or raijuu, literally "thunder beast") is a Youkai that roams The 47 Prefectures of Japan. They are seen as Japanese-culture's blanket explanation for the phenomena of lightning. They are said to be docile and protective on the regular, only to become violent and unpredictable at the drop of a hat.
Raijū often switch between corporeal form and pure lightning, though the appearance of the corporeal form is erratic and tends to fluctuate. Its appearance differs between a white and blue wolf, to Tanuki, weasels, cats, tigers and various other quadrupeds. Because of this, the appearance of the Raijū in popular culture is barely ever consistent and will often rely on its Shock and Awe powers as its defining trait.
Much like Kitsune, Raijū are a breed of youkai seen as emissaries of Kami worshiped by the population. In the case of the Raijū, they are associated with the similarly-named Raijin, the Shinto God of Thunder and Storms, acting as familiars that carry out his actions on the earthly plane. It is said that Raijū tend to rest within the belly-buttons of sleeping mortals and Raijin would wake them up by shooting arrows of lightning at them. Because this causes great harm to the unwitting human, superstitious people would sleep on their stomachs to protect themselves.
- Ayakashi Triangle: Soga spends one chapter chasing after a cat-sized, quadrupedal raiju (called "Lighting Beast" in English). It has two tails that look like electrode at the end cables, constantly runs around, and turns into electricity to travel through power lines and electronic devices.
- Captain Tsubasa: When Kojiro Hyuuga develops a new signature shot, he names it Raijū Shot, due to finally perfecting it during a thunderstorm. Video game adaptations often include the Animal Battle Aura with the creature itself manifesting whenever he performs the shot.
- Cardcaptor Sakura: The manifestation of the Thunder card is Raijū, the Thunder Beast. It looks like a big electric wolf.
- Digimon Adventure 02: Raidramon is Veemon's armor evolution when the former creature is exposed to the Digi-Egg of Friendship, giving it the quadrupedal physiology of the wolf-like Garurumon evolutionary line and a lightning affinity.
"Veemon armor-digivolve too... Raidramon, the Storm of Friendship!"
- Flower Knight Dakini: Thunder Beasts play an important role in the story as they are created specifically to destroy the Golems threatening the world. They do not possess any electricity-related powers, instead the main weapons of their enemies are destructive lasers called Straight Thunders or Mjolnirs.
- Inuyasha: The Raiju Brothers Hiten and Manten. They're both humanoid (with Hiten being totally human-like while Manten has a monstrous head and yellow skin) and they do care for each other. The anime filler also introduces their little sister Soten.
- Monster Rancher: The character Tiger (originally known as Raiga in Japan) draws inspiration from the raijū, resembling a blue and white-furred wolf with horns that he can shoot bolts of electricity from.
- Otome Youkai Zakuro: A raijū goes berserk in the first episode, giving us a chance to see Agemaki's courage — and the half-youkai girls' ability to actually handle the situation.
- The Rising of the Shield Hero: In "A New Comrade", Naofumi and his party encounter a Nue, but its body gives off a powerful electrical charge like the Raijū.
- Rosario + Vampire: Raijūs are an incredibly powerful breed of monster. They are bipedal, mammalian with horns on their heads and power over electricity. The only example of a Raijū present is Raika, Leader of Fairy Tale's Fifth division.
- Touhou Project: One chapter of the manga Wild and Horned Hermit features Reimu and Marisa finding Kasen's pet raiju and becoming poisoned by its thunder. In Kasen's later appearances in the games, the raijuu (named Mukou) is featured in some of her attacks.
- Ushio and Tora: While Tora has been called a raijū, his actual form looks more like a tiger, and lightning is only one of his Combo Platter Powers. It is not, however, his real species, just a moniker.
- ×××HOLiC: A raijū appears in the form of a crazed lightning ball.
- Yaiba: Shiro Amakusa turns into a giant, six tailed weasel with huge claws for his showdown with the Kid Samurai. However, he doesn't gain any thunder-related ability.
- In Never too Clever, Starswirl the Bearded and Clover the Clever at one point have to deal with a raijū — a wolf-like Elemental Embodiment of lightning that can create storms — that has been terrorizing the pegasus weather workers. As it turns out, raijūs feed on electricity and the creature's attacks were prompted by the pegasi's suppression of naturally occurring storms, which was starving it to death.
- Pacific Rim: One of the kaiju is given the name Raiju. Resembling a crocodile or a mosasaur, it has a three-part head armor that protects its wormlike real head inside. It is portrayed as a fast swimmer with powerful jaws, but possesses no electrical abilities.
- Beyond the Pyramids: Legend of the White Lion: The titular White Lion derives its designation not from having white fur, but from being composed of lightning. The creature is described as a pentacle of the gods and able to take on human form if it suits its purposes. It is both malevolent and benevolent, killing without remorse but also seeking to draw the best out of the humans that take on its challenge to come to Hell's Gate.
- Samurai Sentai Shinkenger has perhaps the strangest example of this youkai in fiction in Happouzu (Crustor in Power Rangers Samurai). Like all the ayakashi, he is the In-Universe basis for a youkai, and despite being a walking mass of barnacles, he's the raijū. Might have something to do with the orbs of fire and lightning he can shoot from his body.
- Ultraman Taiga has the Monster of the Week, Gorothunder, whose motif is based on the Raijū. Its design is inspired by Shinto lightning god and it can summon thunder and lighting.
- Pathfinder: Raijus are creatures native to lightning-wracked regions of the Plane of Air, but are often flung to the material world by the elemental fury of the storms they live in. They naturally resemble small, foxlike creatures crackling with electricity, but are actually born as spheres of living electricity and, when in the material plane, they usually take the forms of small, common mammals from their new home area so as not to stand out. They return to their true forms during the fits of furious activity that lightning storms engender in them, and are constantly seeking to return to their home plane. There are also kaenjus, rarer relatives of raijus that come from the Plane of Fire instead.
- Dungeon Crawl: Raiju are late-game enemies that take the shape of a blue hound and can turn into living lightning at will.
- In Genji, the Nue boss from the first act is replaced by its palette-swap cousin Raijū, who uses lightning rather than non-elemental attacks and whose claws are needed to make the game's Infinity -1 Sword for both Yoshitsune and Benkei.
- Kabuki Rocks: Raiju are enemies first encountered in the Mosaic Cave on Awa. They resemble dogs with lightning bolt as ears and an electric field around them.
- Monster Hunter:
- Monster Hunter 2 (dos): Rajang is a Thunder-type monster, can appear like a ball of thunder or fire, has yellow and black fur, and looks like the monkey-like depiction of the raijū. It has only one tail, which can be cut to make it lose power.
- Monster Hunter Portable 3rd: The Zinogre is also based on the raijū, being a wolf-like monster capable of generating powerful electrical shocks.
- One of the bosses in Nioh is the Nue. Much like in Genji, the Nue in the game adopts various aspects of the Raijū, most notably the emphasis in its tiger-characteristics and its Shock and Awe powers.
- Pocky & Rocky Reshrined character Ikazuchi is a weasel-like creature who has weather based powers and primarily fights using lightning-based projectiles. Her character blurb in the game's character trailer even outright calls her a Raiju (or Thunder Beast in English).
- Pokémon: A number of Electric-type Pokémon are based, to a greater or lesser degree, on the raijū.
- Raichu, a large yellow-and-black rodent (likely based on the Tanuki-like appearance) with a lightning-shaped tail and an obviously inspired name.
- Jolteon is a yellow, mammalian creature with spiky fur and is known as the Lightning Pokémon; actual lightning sometimes strikes near it, even.
- Raikou, one of the three Legendary Beasts, is the most direct derivative of the mythological raijū. It resembles a black-and-yellow saber-toothed cat with a zig-zagging, lightning-like tail, and it's said that thunderstorms follow where it goes.
- Manectric resembles a blue-and-yellow wolf with a prominent lightning theme, and it physically resembles the (main form of) raijū more than Raikou itself does.
- While Thundurus is primarily based on Raijin, the thunder god that raijū were sometimes associated with, its beastlike Therian Forme is more heavily based on the raijū itself.
- Zeraora is a yellow, feline 'mon with black and blue lightning bolt-shaped markings and is classified as the Thunderclap Pokémon.
- Shin Megami Tensei: Raijūs appear frequently as beast-like creatures made of lightning.
- Yo-kai Watch: Rai-chan are a breed of yokai introduced in Yo-kai Watch 4 based on the raijū. Their Lightside forms are Rank SS and have the same cutesy toon-design as your average youkai. Their Shadowside form are Rank SSS are much more intimidating.
- Monster Girl Encyclopedia: Raiju are a species of lightning-controlling magical Weasel beast-women from the Zipangu region. They are a bold, ferocious and impulsive race, who are driven by lust above all else. They are particularly adept at using their electrical abilities to provide electrical stimulation during sex.