Michigan's rule is that out-of-state students who live in Michigan while they are attending school are not considered Michigan residents or part-year residents and should file as non-residents. Therefore you are still a Wisconsin resident for tax purposes. See page 6 of this reference: https://www.michigan.gov/documents/taxes/1040_Book_-_Instructions_Only_508950_7.pdf
An added wrinkle is this: Michigan and Wisconsin have tax reciprocity. If you live in one and work in the other, your W-2 wages are taxable only in your home state. So, for tax purposes, any W-2 earnings you've had in Michigan are considered Wisconsin income, and taxable by Wisconsin.. If all your earnings in MI are W-2 wages, you need only file a Wisconsin return. You would only need to file a non-resident MI return if you had MI income other than wages. If that's the case you'd need to file a non-resident MI return AND a regular WI return.
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
