Akira Tennou, an unremarkable thirty-five-year-old man, gets hit by a truck on his way home from work and, after a brief experience in some mystical limbo, wakes up in a gloomy forest. This forest is beset by a sinister black mist—his memories of his little sister's lectures about fantasy novels tell him that it's probably under an evil curse. He soon encounters one of the forest's residents: an enormous silver wolf. At first the creature is hostile, but he finds that it's been corrupted by the same black mist, and he only needs to cry "Purify!" to banish the curse and heal the wolf. Akira discovers that the residents of the forest are all animals, and once purified, they are far from feral beasts.

His newfound magic allows him to speak to his new animal companions; he finds that they are intelligent and the rightful rulers of the forest. Akira decides to explore this new world, purifying the land and its inhabitants as he goes. But the source of the cursed mist can't be far away...

(Source: J-Novel Club)