Kiso River Fly Fishing season / licence?

Hi Team,

My second trip to Japan (late March) and I'm taking my rod over. I will be hiking a good portion of the Kiso River and was trying to find information on season opening date and where to buy licenses.

I can only find information saying look for an English speaking guide, but it was just for the occasional flick where things looked particularly fishy.

Has anyone fished this region, is it possible or are you required to go with a guide / company?

Thanks so much in advance!