Here are a few adventure ideas ripped shamelessly from Japanese sources. All adventures take for granted that PCs are under orders of a lord and follow his decrees largely unquestioningly. If not, DMs will have to find different reasons for adventuring. Try to enjoy the weirdness of the adventures and not punch them up with combat too much to please western audiences. Make interactions and social restrictions a vivid part of the world, and you should have the right feel.
1. Possession (Genji Monogatari)
Several murders of night watchmen and travelers have occurred and PCs must find the cause. The bodies are mutilated as if mauled and partially eaten by some animal. Either by stakeout, investigation, or scrying they find that a noble lady is possessed by a demon which turns her cannibalistic at night. The lady is kin to their lord, so they must find a way to out the demon without harming her, all the while keeping the incident quiet from villagers who might raise arms to protect themselves.
2. The Peony Lantern (Lafcadio Hearn, Kwaidan)
A nobleman has started wasting away, losing strength and becoming wan due to sleepless nights. He refuses to divulge the cause of his lethargy, and so the PCs are sent to find out. By either surveillance, consulting a medium or other means, they discover that the lord is haunted nightly by the ghost of an old lover he spurned and caused to waste away from grief or commit suicide. PCs must drive away the spirit, either by satisfying its demands for justice, or convincing the nobleman to repent and either become a monk or publicly shame himself by professing his dalliance.
3. Space Girl (Osamu Tezuka, Hi no tori)
A peasant’s wife has run away while he was at war, and now returning as a minor noble he asks the PCs to find her and his child. She has left behind a magic kimono of shimmering, unearthly colours that radiates magic. The kimono can only be worn by female characters, and transports them to the moon, where the wife originally came from. The kimono-wearing character can miniaturize two other characters and carry them in her sleeves, but any more PCs will have to find alternate transport to the lunar surface. The moon people are pacifists but also great sorcerers using magic items, and PCs will have a hard time convincing the woman and her now grown son to return to war-torn earth and live with a former soldier. One complication may be that the son wishes to return but the mother doesn’t, forcing PCs to help him make his escape back to earth. Another complication is that miniaturized characters stay that way on the moon.
4. Wolf Head Kashira (Osamu Tezuke, Hi no tori)
PCs are ordered to stop a bandit chieftain has been terrorizing the mountain roads, but investigations shows that he is only attacking the wagons of a certain clan. The chieftain is said to have a wolf’s head and is magically protected by animal familiars. If PCs meet the wolfhead, he reveals that he is the clan’s disappeared heir, whose face was flayed by the current clan head, covered with a wolf’s head as an insult, and then left for dead. By some strange magic the heir recovered but with a wolf’s face and animal powers. He will only stop his attacks when the current clan leader is dead and the heir’s rightful place and face restored to him. PCs may have some serious questing to do to achieve this.
5. Moth woman (Osamu Tezuka, Dororo)
Children from a small village have been disappearing at night from their houses, and the lady of the village has asked for help to calm her subjects. PCs are sent to investigate and sensitive characters or priests may be lead by the beckoning of ghostly children to the run down old hut under which their bodies are buried. Under the tatami mats in a tunnel are the children, wrapped in cocoons and undergoing a horrid transformation into mothmen. Following the tunnel to its end brings the PCs come face to face (tail?) with a grotesque moth creature, who turns out to be the underside of the lady of the village. They must battle to stop her while defending themselves from the child-mothmen she awakens with her screams.
6. Dirty Old samurai (Shigurui/Vagabond)
In a small village on the stormy coast, a veteran samurai lives and protects villagers from bandits and rival clans. On a visit to the village, PCs see that the old bushi has gone rogue, is often blind drunk, tests his blade on villagers, and takes their daughter’s maidenhood when they are 12 or 13. The samurai must be stopped, but as he has higher rank than the PCs, is an expert swordsman, and has magical arms and armor from his past adventures, they will have to find some subtle way to discredit or destroy him. Note that the samurai is paranoid and wily, and will not fall foolishly into any old trap, but will kill all who shows animosity towards him. He is just as deadly when drunk or sober.
7. Freak Circus (Suehiro Maruo, Shojokan)
The circus comes to town, and the elder son of the lord starts dallying at the tents of the freaks. The PCs are sent to drive the freaks off, but must deal with threats including Snakelady, who can shoot poisonous snakes from her orifices; Rotting Man, a bandage-enwrapped ex-soldier who cannot be killed by mortal weapons but simply loses gobbets of flesh; Giant Baby, an ogrish man with the temper and jealousy of a child; The Mouth, a limbless obese giant who rolls over PCs attempting to crush then eat them; and Dr Ching, an evil sorcerer from the continent who can thrust characters into their nightmares. If PCs are victorious, they find the son in a sorcerous sleep, which may require questing for holy objects to break.
8. Shadow Banquet (Lafcadio Hearn, Kwaidan)
A distraught young musician begs the PCs to save him from ghostly samurai who visit him every night. He hasn’t slept in days, and if he falls asleep at night when the samurai come to hear his music he will be forced to join them in the hell between worlds. PCs can either fight off the samurai if powerful enough, or more likely should quest to various temples and apothecaries for magic ink to write wards all over the musicians body and Buddhist Sutras on paper which can bind or wound the ghosts.
9. The Phoenix (Osamu Tezuka, Hi no tori)
The high priestess of the clan is growing old and has started fearing age and death. She sends the PCs to an island where the legendary phoenix has been spotted, with orders to kill it and bring back its rejuvenating blood. The bird is deadly and fearsome, but getting to its lair is made difficult by the presence of savage natives who revere it as a god. If players do manage to kill it and retrieve its blood, which is always boiling hot, the death of the bird causes an eruption of undead who begin plaguing the countryside. PCs may seek to revive the bird, which can only be accomplished by throwing its body into a volcano. If they do bring its blood back to their mistress, she drinks it but is ironically consumed alive by fire bursting from her innards, also giving birth to a newly formed phoenix which flies off back to its lair. Irony!
10. The Spirit Gun (From a Big Comics Original supernatural manga about an antiques shop whose name and author I forget)
Officials of the clan are being assassinated at night by a young gunman who disappears like smoke whenever guardsmen give chase after a killing. PCs are given sketches of the assailant and must try to find him. If they go to the burakumin (social outcast) district, they will find that the boy was from there but died many years ago, and that his father is a woodcutter on the edge of town. If they meet the woodcutter, he is a kindly old man who invites them in for tea, and tells them the tale of how his son died out hunting. In truth, the youth was killed accidentally by a noble also out hunting, and his spirit now haunts his rifle, which the father keeps hidden in his house. PCs will have to assuage the spirit by somehow getting it justice.
11. The Fox Stole (as above)
A lady of the clan is found strangled in her chambers, but with no signs of struggle or intrusion. If characters investigate thoroughly, they find a few items of the lady’s clothing are missing. A few nights later another lady dies in the same way. If characters investigate, they will find more clothes are missing, and one item, a fox stole, is on both missing item lists. If they interrogate the handmaidens, they find one in either case has sold their deceased mistress’ articles to support their family. Tracking down the fox stole to the antiques shop where it was sold, PCs find that it has just been purchased by another lady. They have scant hours to find the cursed garment and stop another killing by the fox stole, which was cursed years ago by a rival clan to strangle the wearer when placed around neck and shoulders of a noble of the clan.
12. Mud Flinging (Ge ge ge no Kitano)
Construction on a new fort has halted as workers are attacked by a strange giant humanoid rising from a nearby pond who flings enormous balls of mud at them. Men have nearly smothered under the mud, and a death will occur if something isn’t done. The PCs are sent and are easily overwhelmed by the creature. Any PC speaking youkai language will learn that the creature is yelling “tanbo kaese!”, or “Give me back my fields!” It is actually the guardian god (kami) of rice fields that have been destroyed The PCs must find a place for the youkai, preferably in a rice field that is clean and well-kept.