Higashi-Shinagawa Marine Park (東品川海上公園) 東品川海上公園
It is the park in episode 5 of the drama's second season.
A park on the Shinagawa canal, which local residents call ‘the Miffy park’ because of its rabbit-shaped play equipment.
Tokyo
Aomono-yokocho, Tennozu Isle
Kotaro Lives Alone
It is the park in episode 5 of the drama's second season.
All the places from Kotaro Lives Alone
https://theanimetrip.com/luoghi/parco-marittimo-di-higashi-shinagawa