Shadow brokers are Japanese data brokers who consist the domestic crime infrastructure and commit a ransomware. This is the main profile of them.
At the same time, this guy can speak English. I am not sure how good he is, but at least they can make himself understood in English and can communicate with foreign criminals. These foreigners are highly likely related to the equation group and are highly likely to hire the Japanese data broker to disguise their identities.
The shadow brokers have a skill-set to hack the corporate server, but I doubt they can sneak into the NSA server. It is more like they obtained the data from others, though their action was a total breach of the national security and it is assumed to be a felony. Japanese police should have an interest in them, but also the CIA and FBI should come to Japan to investigate them.
I am not sure how many data brokers are in practice in Japan, but there are limited number of players holding a capability of hacking and ransomware. I assume Japanese authority can narrow down the suspect within ten probabilities. When they have registered as the private investigator in Japan, the police know who they are at least. It is necessary to register as such to conduct a private investigation in Japan, which is applicable to the data broker if they would like to sell their product in the consumer market.
One more addition, but the member of this global crime organization have likely visited Japan and knew the brokers’ English capability through the conversation. If we can catch shadow brokers, we can tail others as well.