In the past few weeks, 2 hot spots were found in Setagaya, and both were caused by the Radium226 bottles coincidentally.
The distance between the 2 locations are about 7km.
However, both of the hot spots were found by the same person.
(His twitter account: https://twitter.com/#!/n0ri_tiki)
Mr. Nori “seems like” to be an anti nuke activist.
From his twitter, he searches for hot spots to save people, like everyone else.
He will probably find the third hot spot in Setagaya, and there will be a radium-226 under ground again.
(Source)