The Japanese construction business targeted by the family office related to Nintendo Co.’s (7974.T) founder is fighting back and asking the government to examine suspected foreign ownership violations.

According to the letter obtained by Reuters, maritime construction business Toyo Construction Co (1890.T), 27% controlled by Yamauchi-No.10 Family Office (YFO), requested the government’s approval this month.

Toyo, which maintains port facilities and builds seawalls and other infrastructure, demonstrates how national security regulations may increasingly influence takeover conflicts.

On Tuesday, Toyo revealed it had requested a family office investigation from Japanese authorities.

Last year, YFO, which oversees almost $1.5 billion of assets for Nintendo’s founding Yamauchi family, prevented an industry rival’s purchase of Toyo by offering a higher price.

YFO owns 27% through three Cayman Islands-registered investment firms with less than 10% each.

Toyo said that its firms are in strategically critical “core areas,” requiring investors to report to the government before obtaining a 10% share.

In its letter, Toyo stated YFO breached the laws by not alerting the government since the three Cayman Islands-registered automobiles are linked.

The government says violating such restrictions might lead to fines, jail, and the return of all or part of the financial share.

Toyo also criticized the three vehicles’ investment disclosures. In regulatory filings, they asserted “pure investment,” but Toyo added in the letter that they may make key ideas.

“We would not cave in to pressure based on groundless assertions,” YFO wrote Reuters.

The three investment vehicles had distinct directors and were not closely connected as defined by law regarding capital structure.

“We consulted authorities during the acquisition of Toyo Construction shares and the takeover bid. Regulators have never indicated a problem “it claimed.

Last month, Toyo unveiled a mid-term business plan to increase value and shareholder support. By March 2028, it pledged to treble its dividend payout ratio.

It aims to enter offshore wind generation and aggressively expand its international construction companies.

Banjo Yamauchi, the 30-year-old biological grandson and adopted son of Nintendo’s third president, Hiroshi Yamauchi, who converted the playing card company into a video game behemoth with Mario and Princess Zelda, founded YFO in 2020.