In case of M&A, opposition shareholder can sell its shares to the company at fair value
1) Shareholders that do not approve its merger (shareholders of a company that is resolved to be merged by another company) can claim to sell its shares at fair value (Company Law #785).
2) To withdraw its request to sell the shares, shareholder needs to get approval by the company (meaning, you can not withdraw its request to sell your shares freely.) (Company Law #785(6)).
“Fair values” usually menans “net asset value” or valuation by DCF (discount cash flow) method.