FYI, betobeto-san is a youkai that is formless and is said to follow people walking on the night road. Its name came from the sound of wooden sandals clacking. Normally, you can't see it hence Buchio didn't notice him from the start.
@Nixnaw You can read this page https://yokai.fandom.com/wiki/Okuri-Inu. It is basically a type of yokai that follows people who are walking along mountain paths at nighttime. If a person fall over, they will eat that person. But if you don't fall and keep walking firmly, their presence actually chase off other youkai and wild animals that want to eat you. Depend on the region, the animal species is difference. Some regions call them Okuri-inu (dog), some call them Okuri-okami (wolf) or Okuri-itachi (weasel).