My office window used to be right next to the plaza they go to first, "Kampin tori". I saw a lot of good skating go down over the years during my workdays. It was especially sick when pros were visiting for contests like Helsinki Hook Up or its predecessors. They'd always end up there.
By the way, that place has sucked ass for years, it used to be good when it was new and everything was smooth. Now the asphalt is rough, the tiles are rough and uneven, there are gaps between the blocks. I don't think too many people skate it anymore. It definitely used to be a hotspot but not worth visiting anymore. There are good spots around, but Kampin tori is not one of them.