In episode 10 of the anime monster musume no iru nichijou, this non-human girl appears here:
and here:
She then appears again very briefly in episode 11:
No other mention is made of this character, but the presence she's had has been too great for this to be a mere coincidence. Who is it?
The character in the pictures you've posted is Polt. In this Wikipedia link, she's listed under the supporting characters of the manga Monster Musume.
Polt is a kobold. She is the leader of the local gym, the "Sports Club Kobold", and seems to be rather hyperactive. Sport is her life (any and all sports, including fishing) and she strives to provide the best possible experience for her customers. She is depicted as a fur-clad humanoid with tail and ears like a dog—she even wears a leather collar—but with a more flat, human-like face. She usually wear shorts, T-shirt and track shoes. Polt seems to be trusted to a higher degree than other liminals: she has her own business and is allowed to go out on her own. When Draco and Lilith are placed on parole for being out without host family supervision, Polt is placed in charge of them.
The Wikia link for Polt gives detailed information about the character. Her appearance is described as:
While her species is a Kobold, a Germanic sprite that can take many forms, she appears as an almost human woman with a wolfen face, including a muzzle instead of a nose, and a wolf's tail and ears. Her body, in accordance with her occupation, is very athletic; having muscular arms and legs and a trim abdomen. Her breasts are of average size, in comparison to other characters more prodigious breast sizes. In her debut, she wears a midriff revealing black shirt with the sports club's name on it and an unzipped track coat on top; jean hot pants; thigh straps and wristbands; a dog collar and athletic sneakers.
This is the link for the Google Image Search for Polt.
As has already been mentioned, she is a Kobold named Polt and has rights most other extra-species people don't, such as being allowed to go wherever whenever without an escort.
In the manga version, she is a frequent supporting character, owning and running an extra-species gym where the girls are trial customers, as well as Kobold Stadium which is an Olympic scale establishment. She is a complete fitness nut who is always trying to figure out how to make her gym useable by all extra-species body types and frequently "volunteering" to coach people she thinks could use more exercise... whether they asked for it or not.
