Dr. Takayoshi Doi was arrested in connection with allegedly buying $46,000 worth of NEM that had been stolen from the exchange.
The arrested men are accused of purchasing stolen NEM on the dark web, violating laws that were set up to tackle organized crime online.
The Tokyo-based cryptocurrency exchange has begun reimbursing customers who have lost their funds in the January theft of some $530 million worth of NEM coins.
Investigators are looking into the possibility that an overseas hacker group has gotten its hands on Coincheck’s encryption keys.
A total of 82.4 million petro tokens are offered for the pre-sale phase, according to the cryptocurrency's white paper.