Fishing rules (license and boat/float tube)

Hello

I understand there’s some basic rule of no fishing license for salt water and in some area like river that needs license.

Is there an easy way to check it online each area if it’s needs license or not?
Also I want to use float tube to fish in some river or dams, again how can I check if it’s okay to use or not?

I want to fish early mornings so am unlikely to be in an area where a shop maybe open to ask at that time.

Please reply if you have experience or can provide some detailed answer.

Thank you.

Quick Goggle-fu point to this site

https://umiduri-startguide.net/213

and within it there is a link to 遊漁の部屋(Recreational fishing room) which have more details on recreational fishing rules and regulation for different prefectures.

https://www.jfa.maff.go.jp/j/enoki/yugyo/

I looked at this some years back for someone. The answer was "location dependent". If going fishing (fresh water) easiest is to visit a local fishing shop to check the rules and get a license for the day (usually required. For salt water, usually no, but not always.