However, for tourists and visitors, the one easier to find is Odaiba or お台場海浜公園 is a public seaside recreation area on reclaimed land in Tokyo Harbor. Remember Odaiba is in a pubic park so being nude should be done with caution.
If you'd like to go or would like to join me there (when it warm enough), you can contact me for directions.
Here I am at the X-spot. I like being seen by clothed or partly nude men.
This is just beyond the wading pond, right on edge the concrete embankment. It's usually where I park my bicycle. The Inagi Ohashi Bridge can be seen in the background. On the far left and middle of the photo is the edge of the wading pool.
There's a small tree in the foreground (ignore it), but it's on the embankment which is a flood levy built out of concrete and concrete tiles. Look further along and towards the very center of the photo, and you'll see a tree right on the edge of the embankment. It's a large tree with abundant branches that spread out like an umbrella.
Just before that tree, you can go down the concrete embankment to a trail. There should be a trail worn between the tall grass and bushes - a least in summer, early fall there is. The trail is about 25 meters long and leads up into the dense ticket where the cruising and nude sunbathing goes on. If you make your way into this hidden islet (usually no water), you will find a low area among the trails. There are 3 walnut trees and some willow trees there which is where the fun goes on.
Sometimes guys make a pretense of sitting or standing around that area near the tree. That way they can see who is going in to cruise and will follow if they are interested in pursuing. Sometimes, a fellow or a coule of fellows will sit and smoke or have canned drinks while they are waiting.
I haven't been there enough to know any patterns for what time of day or which days are busy. Fridays can be busy. I once saw a naked guy scurrying off in the bushes beyond the inland island thicket. Saturdays and Sundays and holidays would also tend to be busier... but there can be no guarantees.
Map / Directions: See the Google map below. You can walk (about 18-25 min) from Musashinodai Station (Keio Line from Shinjuku, take an express train to Chofu, then a local train to Musashi-no-dai). The wading pond visible in the above photo is located on the map. There a man-made stream that runs from the wading pond to the right (north west) for about 150 meters. The cruising spot is just beyond the wading pond.