The Ancient Magus' Bride S01 E07 Talk of the devil, and he is sure to appear.

The dog, with its flowing, black hair and burning red eyes, called Chise by the name "Isabelle." The Church's final request is to investigate a black dog that emerged in a cemetetry, but the black dog ends up saving Chise from danger. Meanwhile, Renfred's apprentice, Alice, is also on the move, looking for the black dog.