We're hosts to a parasite.

Far from the rapid modernization of the city lies a village strongly rooted in a prior age. It is lush, but people say that

It's cursed by the mountain gods.

The flowers, vines, moss that one would expect to feel underfoot instead herald every spring from the villagers' bodies. They slowly die as if rejoining the mountain, and the curse, nicknamed "Kasou" (cursed grass), inflicts them indiscriminately.

But for one.

[Translated from The Official site summary]