LINE was found to have broken rules related to payment tokens used in an online game, Reuters reported.

The Kanto Local Finance Bureau said the tokens are a prepaid form of payment, and funds collected must be reported. Companies with unused deposits of more than JPY10 million ($91,500) made by customers must “park” half of the amount with a division of the justice ministry, in accordance with Japanese law.

LINE apparently did not do so because it did not consider the tokens a currency, and hence did not believe the deposit needed to be reported.

At the end of March, the shortfall totaled around JPY12.5 billion. LINE spokesman Icho Saito said: “We will respond in good faith to the Bureau’s instructions”.

Last month regulators raided LINE’s offices as part of a routine investigation, and it is possible they were looking into how customer’s money for tokens is handled.

In March it was reported that LINE is mulling a $2 billion-$3 billion initial public offering that could take place before the summer.

According to App Annie, LINE owns the three top-grossing apps of all time (LINE, LINE Play and LINE Manga), “fueled primarily by revenue in Japan”.