It is Sakuragawa Park facing Shin-ohashi-dori St. on Irifune 1-chome.
The map below is on the red frame.
It is located just off Hatchobori Station, where the JR Keiyo Line and the Tokyo Metro Hibiya Line
intersect.
This was the place where Hatchobori was located in the Edo period, and was called Sakuragawa in the Meiji era, and was reclaimed in the 1940s and became the current park.
Cherry trees 
(Yoshino cherry tree) are planted and shaded, making it an urban oasis in the office district.
Many office workers and passers-by are resting in the shade of the park, especially during the hot lunch break
.
Next to the park, the "Iriichi Kannon Bodhisattva" is enshrined.
On the same site, there is also a prayer stone that is said to be effective for toothache.
In the park, there is also an explanation board for "Hatchobori (Sakuragawa) Ruins".
