There are many small creeks in Tokyo that have been turned into pedestrian paths. In my neighborhood, they are modestly landscaped. In Shinjuku, there’s Shinjuku Yuhodo Koen Shiki no Machi (新宿遊歩道公園四季の道), an amazing green corridor with mature trees between the department stores of San Chome, Hanazono Shrine, the packed bars of Golden Gai, and Kabukicho.
Oddly, my very detailed Tokyo City Atlas does not include the path’s name. It’s easy to miss it, but once inside it feels like a magical passageway, full of life during the day and at night. Green corridors take up minimal space, and are perhaps more useful than small parks since provide a path between places.