If you’d like to support people doing things sustainably, you should head down to Yoyogi Park for its regular Earth Day Market. Some 52 stalls line the ‘Keyaki Namiki’ stretch between Shibuya and the main part of the park. You can buy organically grown fruit and vegetables, fair trade goods, and handmade crafts. They also have a special recycling setup. Bring leftovers like used tempura oil in exchange for ‘R’, a special currency used only at the market. You can visit the Earth Day Market website to learn more about it and check when the market is being held.
The market runs from 10 am until 4 pm. Closest stations are Harajuku/Meijijingumae on the JR, Chiyoda and Fukutoshin lines and Yoyogi Koen on the Chiyoda Line.