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.

(2) 都営墨田一丁目第2アパート (website 1; website 2) = Toei Sumida 1-chome second apartment

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“.