The people of Shori know that each fish is unique and valuable. With the many varities and flavors that come from the stepped mineral lakes of their land, no two lakes have the same fish in them. Households for families and servants care not just for the land surronding the lake, but the animals in the lake as well. A household with out it’s familiy fish is a ruin and abandoned.
Last week, the house Min-ri saw some strange fish floating in thier lake. They weren’t any fish that lived in thier lake, nor the house Kouto-tsun, the house directly upstream. When they sent messengers to house Kouto-tsun, they returned to tell that the house was abandoned, but intact. No one answered their calls and no bodies were found. Worried, but not knowing where to turn, they sent to the capital for help discovering the source of the dead fish.
Ideally, the players are the answer to that plea.
When they arrive, they are shown a freshly captured corpse of the fish. Since they sent word, more and more of the dead fish have been toppling over the falls every day. They have erected a series of stacked nets to keep them from thier lake, but if the sickness is in the water, they are lost.
The fish is barely recognizable, a slimey purplish salmon, with long fins wrapped on strong, sharp bones. It has V shaped gills and an inverted V shaped tail. Rotting fish never smell good, but this one either smells especially bad, or has been rotting long before it was caught in the Min-ri nets.
When the players venture to the Kuoto-tsun house, no one can be found. Close inspection reveals Red Bear tracks on the ground and many more dead fish in the lake. Very close inspection shows two unusual things - the tracks are very orderly, all leading further up the plateaus; and inside the house are gentle and careful marks from Red Bear claws. Either the Red Bears were gentle and opened the doors quietly and mannerly, or a person wearing Red Bear paws as gloves did.
Red Bears are grizzely sized bears with reddish fur. They are very territorial and primarily eat fish. The people of Shori hunt them for food and to keep their own fish safe.
When the players go upstream, they will encounter a couple Red Bears moving with unnatural silence and cunning, ambushing the party and driving them towards a crevise in the plateau cliff, cutting off escape. The players must kill them to survive, but a normal hunting party has a dozen trained hunters to kill one bear. The players better have come well prepared.
Provided they’re still alive, it the players reach the next lake, the will find it covered with dying fish. The fish are barely alive though, but something is killing them. Sitting under the falls from the higher plateau is a horror, a demon from another plane. When he spots the players tampering with his plan, he slips under the sickly fish and makes his way towards the players, then attacks suddenly. The horror is fast and armed with five long tentecles ending in hooks, but cannot hold it’s breath more than a turn. If the players can drive or drag it out of the water, it will be clumsy and an easy kill.
The horror was the source of the dead fish, filling them with a kind of demon pheremone to make them breed and attack creatures. The Red Bears ate some of the diseased fish and came under the horror’s control and silently slaughtered the Kuoto-tsun in the night. Once the fish tainted by the horror die, the remaining fish will be ok, the horror’s taint dies with it.