This character is from the otome Wizardess Heart. 

Nidhogg has been said to be a creature existing before the land of Gedonelune was founded. In legends, he used to be a giant serpent that could steal magical power. Since then, he had been sealed away with the help of the Largene twins Lars and Clives. He is Clive's familiar and has a weakness for desserts. Nidhogg also has a very high and mighty attitude. 

Despite looking like your typical goofy familiar, Nidhogg still has the capability of being a villain. 

Voice: Medium to deep pitched, shouty, possibly a bit annoying. A deeper pitch is more preferred due to the game lore stating Nidhogg's voice is deep, but is not required. One of the members from the casting team suggested he should sound like Amanojaku from Ghost Stories (example #3). So either one of these voice types could work. A combination of both may also work!

Example #1(but deeper), Example #2, Example #3 (Amanojaku)