I guess ocean fishing is prohibited here in japan when you dont have a license or permit to do so.
I had been tried once sport fishing not in Tokyo but in Tochigi ken. It was really fun because when you're luckily catch the one big Japanese Carp (koi fish) you will get some gift or rewards.
In Numazu City, there is a season for fishing (usually in Summer). We went fishing at a port several times in the summer. It's fun because there were a lot of people (usually groups of friends or the whole family) also fishing in the area. There is no entrance fee needed. All you just need is your own fishing equipment. Some would just set up a mat, bringing obento, drinks and snacks for a whole day fishing activity. Fishing in Numazu is not very strict.