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
This is the link for the Google Image Search for Polt.