Disclaimer: I don't own Naruto or any of its characters.
Funayuurei
In Konoha, as in most other Hidden Villages, All Hallows' Eve is a night of contradictions. It was originally a festival meant to honor the dead, and in a shinobi village there are many dead to honor. So there are solemn ceremonies at temples, where food offerings are left in the name of ancestors and friends, and lanterns set afloat on rivers to symoblize the soul's journey to the next world. But it is also a night when children defy their fear of ghouls and ghosts and things that go bump in the night by dressing up as those creatures and treating it as a game.
The adults, perhaps remembering their own carefree and innocent days as children, indulge these games by handing out candy to the costumed little ones. Some of them get into the act by dressing up as well, and ninja are known to sometimes scare the children who show up at their houses by appearing right behind them on the porch, seemingly out of nowhere.
Shimura Danzou does not participate in any of this. On All Hallows' Eve, he locks every door and window to his house, turns off all the lights, and sits in the dark. He unwraps his arm and surveys the darkened room around him with the power of the Sharingan, the unblinking eyes remaining alert from dusk until dawn. His back is rigid, his face stiff, his feet planted firmly on the floor. To a casual observer, he would appear to be merely disciplined, but a skilled shinobi would recognize that the true origin of his bearing is the tension of fear.
Because all the lights of his house are off on this night, people rarely stop there. Adults don't knock on the door to invite him to temple ceremonies, and children don't usually ring his doorbell seeking candy. Every so often, though, a group of kids will decide that the darkness of his house is simply a ruse to make the place look scary and forbidding, another example of adults "playing along" with their games. They'll climb the steps and rap on the door, and inevitably there will be no response. After a few moments of silence, the children depart, having no idea of how their simple, innocent gesture has made Danzou's heart race and his breath quicken.
If anyone knew of this, they would surely find it odd. Whatever else he may be, Danzou is an accomplished ninja, and a consummate survivor. He's faced fearsome enemies, and for him to be afraid of spirits and shadows seems, at first glance, ridiculous.
This, of course, is because they don't know what Danzou has done.
In a ninja village, everyone, even the civilians, knows what chakra is. It's the energy that powers all life, and it comes in two flavors: physical and spiritual. Shinobi perform ninjutsu by mixing the two. This is common knowledge, but not everyone fully thinks through the implications. Physical chakra is tied to the body, and so it disappears when the body ceases to function. But chakra comes in two flavors, and not many people stop to think about what happens to the other half of a person's chakra when they die.
Some do. The Second Hokage thought about it, and he found a way to use tissue from the body of a deceased person to forge a bond between the physical and the spiritual once again, to call back the spiritual chakra from wherever it had gone. Orochimaru thought about it, when he rediscovered and improved upon Tobirama's technique. The attendants of the temples thought about it, and sought to commune with the souls that they believed to be formed from that spritiual chakra.
Danzou has thought about it too, and that is why he remains barricaded in his house on All Hallows' Eve, waiting for the night to pass. And hoping against hope that he doesn't hear the chime of his doorbell, or a knock on the door.
He didn't always do this. The first autumn after the Uchiha Massacre, he hadn't yet thought through the true meaning of the division between physical and spiritual chakra. Of course, he still hadn't bought any candy or dressed up in any costume, dismissing such things as "childish foolishness." But light shone out through the windows of his home, and he was going about his nightly business. A stack of mission reports sat waiting for him on his kitchen table, and a pot of tea was brewing on the stove.
Then there was a knock on the door.
There were no ominous portents accompanying the knock. The lights didn't go out, there was no dramatic flash of lightning, wolves didn't howl in the distance. Danzou registered nothing more than mild annoyance at whatever brat was wasting his valuable time.
He marched over to his front door and wrenched it open. "I don't have any candy for you," he stated bluntly.
"That's all right," answered the lone boy standing on Danzou's front porch. "I don't want any candy." His clothes were soaked through, and water was beginning to pool on the porch under his feet. More water dripped from the ends of his curly hair, and his voice had an odd, bubbling quality to it. His face was a pasty white, and blood trickled down from his empty eye sockets, fading from bright red to pink as it mixed with the water on his face.
Danzou quickly slammed the door shut, locked it, and plastered every seal he knew over it. Every year since then, he's done his best to make it appear as though he's not home on All Hallows' Eve, listening for a knock on the door that he hopes will never come.
He sits in the dark, and remembers what he heard the drowned boy say as the door closed in his face. He's read enough old books to know that there's no consensus on exactly what rules such things follow. Ninjutsu seals, holy barriers, lack of invitation-any number of things are said to keep them out, but the proper protections vary from one author to another. He hopes that the precautions he's taken will be enough, because the boy's final words gave him a pretty good idea of what will happen if he ever gets in.
"I just want my eye and arm back," Uchiha Shisui had said.
A/N: This story was inspired by two things. First, I wanted to do a Halloween story, and I remembered some ghost stories I heard/read as a kid that follow the formula of someone stealing something from a grave, and the deceased person following them to get it back. Second, it occurred to me a while ago that in a setting where the existence of souls and other supernatural beings is a known fact, grave-robbing or desecration of corpses, like what Danzou did to the Uchiha, is completely bloody stupid. In a lot of folklore traditions, such acts are likely to cause angry spirits to come calling, and yet despite living in a world with bijuu, Edo Tensei, and the Shinigami, Danzou's just like, "I'mma go desecrate some corpses now, HERP DERP."
In Japanese folklore, a funayuurei is the ghost of someone who died at sea. (I know Shisui didn't actually die at sea, but I figured it's close enough.)
Happy Halloween!