The answer to your question is yes; you will absolutely need to file a Vermont tax return for 2016. For confirmation of this conclusion, please read what the Vermont Department of Taxes has to say about who needs to (and who doesn't need to) file a Vermont personal income tax return, at the following webpage:
http://tax.vermont.gov/individuals/income-tax-returns/who-needs-to-file
Moreover, if you returned to Vermont after your work assignment in Japan, or if you maintained residency (legal domicile) in Vermont during that period, then you will be a full-year Vermont resident for income tax assessment purposes . . . meaning that your wage (or self-employment) income you earned while in Japan will be subject to Vermont state taxes.
For more details on Vermont residency, for income tax purposes, you may wish to read the following webpage:
http://tax.vermont.gov/individuals/income-tax-returns/who-needs-to-file/resident
Please also refer to this Vermont Department of Taxes publication, and especially Section 10 at the end (where foreign work assignments are detailed):
http://tax.vermont.gov/sites/tax/files/documents/15811.pdf
Thank you for asking this important question.
