This was the first garden I ever visited in Tokyo on my very first day ever of being there back in 2010. Next to the Sumida river with a back drop of the shiodome skyscrapers is where nature and the metropolis fuse.
Entrance is via Shiodome station exit 1 and costs only 300 yen. An Edo period garden with a beautiful tea house on the pond island you can have tea here for 500yen open 9.00 – 4.30
I particularly liked all the water and bridges here and the beautiful koi pond. Also the gorgeous trees so well cared for. A wonderful strolling garden.
Visiting here you are not far from Shiba park and Tokyo Tower, plus the gorgeous Zojo-ji Temple.
So maybe plan your visit to both