“There has been no sincere or constructive engagement from 7&i that would facilitate the advancement of any proposal, contrary to comments made publicly by 7&i representatives,” Couche-Tard said in a letter to Seven & i’s board, released late Wednesday. “Rather, you have engaged in a calculated campaign of obfuscation and delay, to the great detriment of 7&i and its shareholders.”

Seven & i’s stock plunged as much as 9.6% in early trading in Tokyo on Thursday. The Japanese retailer has sought to make a case for remaining independent and has made sweeping changes, appointing Stephen Dacus as chief executive officer, making a deal to sell its superstore business for $5.4 billion, and proposing a ¥2 trillion share buyback and a listing of its US business.

In a statement, Seven & i said was it was disappointed by Couche-Tard’s decision to walk away, but said it disagreed with the “numerous mischaracterizations” in Canadian suitor’s letter. The Japanese company also said it remains “fully committed to our standalone value creation plan” and will move quickly to improve key areas of its operations.

“The moat of Japanese protectionism proved too much for Couche-Tard to cross,” Andrew Jackson, head of Japan equity strategy at Ortus Advisors, wrote in a note. “It was always highly unlikely that this was going to be successful given Seven & i’s positioning as one of Japan’s most successful global companies and the fast closing of the ranks.”

The abandonment of the bid, which would have been the biggest-ever foreign takeover of a Japanese company, deals a setback to hopes of greater corporate openness in a country where executives have long been able to display more indifference to shareholder demands for higher valuation than in other places.

Before the proposal to buy Seven & i became public, an attempt to acquire such a well-known Japanese business at such scale was seen as audacious and unlikely, given the protectionist tendencies of the government and corporate boards prioritizing stability over shareholder value. That view may remain in place for a while, despite changes to corporate guidelines aimed at injecting more vigor into corporate Japan through improved governance and protections for investors.