Its a チビワーム。(chibi worm)
you get it from Ct boxes (the ones from the integer quests)
Its also in eTO, but by the name of kid troy worm.
the image for the pet was also used as a monster in the research lab, and as a miniboss in CT.
(btw what do u think of my sheep?
(in that picture i posted xD))
(shes going 3rd job today >:3)