This square site contains five buildings, split between two housing brands:
(1) トミンハイム墨田一丁目 (website) = Tomin Heim Sumida 1-chome
I believe that トミン (tomin) = Tokyoite or metropolitan citizen, and ハイム (haimu) = Heim, the German word for “home”. It is JKK property #13 [物件番号 JKK13]. It was build circa 2000.
This property was built circa 1996.
In the following maps, one shows the full square property, while one shows the property divided between the two housing brands:
There is a circular park at the southeast corner of the site. On the southern edge of the property is an old-fashioned commercial street with several examples of vintage “billboard architecture“.