Some weeks ago, we went to Rinshino-Mori Park in Meguro/Shinagawa area. Rinshino-Mori was used as a forestry testing area until 1978, so it has a vast area of land with various trees and plants. It is truly a forest within the city. Their playground was great, with a pond kids can play in, slides, monkeybars, swings, etc. I just wish there was more of a grassy area to lie around on. Yuuki loved playing, especially the tarzan swing with mommy: )
