calculated their trading fees,so BitFlyer can be no different to that
as a new exchange it must have some incentitives for traders,probably lower fees is the reason for crazy volumes
Currently BitFlyer's fees are based on various levels of their platform;
Bitcoin easy exchange 0.15% base fee, 0.01% lowest fee (the more volume you generate, the lower the fee will become).
Lightning Spot 0.15% base fee, 0.01% lowest fee (the more volume you generate, the lower the fee will become).
Bitcoin Market FREE
Lightning FX FREE
In this case the volumes are quite justified as Japan has legalized Bitcoin - demand is growing legitimately. Sure, there might be some sort of volume manipulation going on, mainly done to lower their general fee, but for now it's all good. Chinese volumes were so obviously fake, that basically no one was taking them seriously. We'll have to give this exchange time. Bitcoin is booming in Japan, which means that more and more exchanges will pop up, and eventually snoop away customers from BitFlyer as they might get a better deal elsewhere.