This follows the arrest of Square Enix employees Taisuke Sazaki and Fumiaki Suzuki, who allegedly acquired stock in Japanese game development company 'Aiming' prior to the announcement of its new Dragon Quest title on mobile, Dragon Quest Tact.
Sazaki and Suzuki supposedly purchased 47 million yen (about $336,300 USD) of stock in developer Aiming. Yuji Naka has also been accused of having insider information - purchasing 10,000 shares of Aiming stock for 2.8 million yen (roughly $20,000 USD) before the same announcement.
Square Enix has issued an official statement revealing it's working with authorities on the investigation and taking appropriate actions against the suspected employees:
“We deeply regret the great concern this has caused to all concerned. We have dealt with this incident strictly, including internal disciplinary actions taken against the suspected employees."
Since the launch of Balan Wonderworld and his departure from Square Enix, Yuji Naka has been involved in a lawsuit case with the Japanese publisher and developer, after he was apparently removed from the game as the director "about half a year before release".