After the event of Sonic Unleashed, Sonic no longer had his Werehog form, when one day he transformed into his Werehog form and could no longer return to normal, so day and night, he was always a Werehog and all his friends didn't talk to him anymore and he isolated himself in his house in the middle of the woods and now he had become Werehog Sonic.

Werehog Sonic: "...I'm a Monster..."