Cryptocurrency market maker B2C2 is reportedly suing the exchange over major bitcoin trades it alleges were unfairly reversed.
Coincheck, CHBTC, Korbit and Quoine are among a new group of exchanges that have added support for Ethereum's digital currency ether.
A deal between a bitcoin exchange and a payments network will see a bitcoin payment option offered to over 20,000 merchants in Japan.
Bitcoin exchange Quoine, which has to date focused on the Japanese market, has raised $2m with plans for expansion.
Japanese exchange bitFlyer has launched a bitcoin-based crowdfunding platform called fundFlyer, and has already signed up one high-profile member.
Quoine, a new Japan-based exchange, is designed by financial industry professionals and will target the wealth centers of Asia.