Inn stay which inc fishing on a boat

Looking for a inn/place to stay where its close to the sea and fishing out at sea will be offered to us to come along.

You might be looking for a fishing charter - an inn with a boat sound uncommon. You can go fishing on Tokyo Bay if you wanted, or even in the middle of Tokyo.

Wait! I can not teach you anything as same angler.

When?
What kind fish you want?
Do you know what kind of fish that we can fish in Japan?
Solo or group? family? w/wife, kids?

What kind boat you are thinking?
乗合船 oiriai sen、貸切船 kashikiri sen? or レンタル rent?
motor boat?
rowing boat? 手漕ぎボート
sea kayak? シーカヤック (canoe?　カヌー)
raft? 筏(いかだ), floating fishing spot in bay.

Where did you live in Japan? Tokyo?
Do you fishing in Singapore? If so, what kind of fish?

Anyway, small remote island is better.
民宿 for anglers is called "釣(り)宿 tsuri" or "船宿/舟宿 funa yado" generally.

But you can do boat fishing even if you do not book a such yado.

Alsol 2馬力(2PS engine/motor power) max and 3.3m size mini boats is not required boat license.
However, as the number of accidents increases, the Japan Coast Guard is alert.
This is met their patrol and check "臨検 rinken" on the sea.
https://youtu.be/VvrTtRHm_R4

What do you mean with “inc fishing”? Squid fishing???

A hotel/ inn where you’ll meet some local fishermen that spontaneously invite you to join them fishing seems to be highly unlikely. However fishing is very popular in Japan and as PP said you can fish even in the center of Tokyo. I personally don’t fish but I remember seeing this fishing spot a few years ago right at Akasaka Mitsuke and was really surprised by its location right in the center of Tokyo under a highway and all:

4-２６ Kioichō, Chiyoda-ku, Tōkyō-to 102-0094, Japan
https://goo.gl/maps/PrAZ621C8QXBC6UF7

A nice place for fishing in a Tokyo park is this one in Eifukucho. Really feels like a trip to the countryside:

お食事 武蔵野園
2-chōme-22 Ōmiya, Suginami-ku, Tōkyō-to 168-0061, Japan
+81 3-3312-2723
https://goo.gl/maps/3MSTc7UjX3G95NLb6

There are more such places in Tokyo:
https://goofish.jp/spot/tokyo/

Now assuming that you are looking for some more natural fishing I found this webpage, which I think is more what you are looking for. A hotel plus fishing:

https://mobile.rurubu.travel/sp/fishing/

Note that fishing in Japanese is 釣り. The webpage is in Japanese only and frankly has a lot of small print explaining what kind of fishing you can expect there , how much it costs etc. so I would suggest that you should get help from a specialized travel agency either for fishing or a specialized Japanese travel agency that can explain to you in your language the different options the hotels are offering.

If what you want to do is fishing squid the first hit on Japanese google for イカ 釣り 旅行 (squid fishing trip) is this one:
https://tsushima-gbt.com/tours/1736

This is another hit with the same search parameters bringing up a list from Jalan, which is a major hotel reservation page in Japan:

https://www.jalan.net/kankou/spt_35211cb3532084522/

Actually even a google search for squid fishing Japan brings up some possibilities, e.g:
https://visit-nagato.com/en/activities/squid-fishing-experience/
There are more.

Enjoy your fishing research and your fishing trip to Japan!

I've stayed here before and they do fishing tours! Not that cheap if your one person, but better priced with more people. It's a bit of a distance from Tokyo though but the new Shinkansen to Itoigawa made a difference...

http://pcrew.travel.coocan.jp/eng_index.html