Black substance (cyanobacteria) is spreading all over Kanto area.
The very similar substance was found in Kashiwa Chiba, where is known to be a hotspot.
↓ It looks like mixture of lichens and dried soil.
↓ 3.44 μSv/h from 200g of the sample.
↓ The person who found this has been having health problem, burn on finger (for 3 months) and the bruise on thighs (for 9 months). The black circle on the left bottom of the picture is the size of the bruise back in July. It’s growing.