Utsuho Reiuji is one of Satori’s pets. A Hell raven who has lived in the underground world since before it was separated from Hell. Her job is to regulate the flames of the Hell of Blazing Fires.
Her abilities come from the god of nuclear fusion, Yatagarasu, and were granted to her by Kanako in the god’s attempt to turn the Hell of Blazing Fires into an energy source for Gensokyo. Essentially, this means that Utsuho’s own body actually houses a divine spirit, technically making her into a branch shrine for Yatagarasu. Apparently, the duller the holder of the power, the better they can utilize it.