"Rikishi seal" is a common name in the streets. 
The real thing is such a sticker (the place is affixed from the telephone box in front of 
Starbucks along Eitai-dori St., just outside Kayabacho Station Subway Exit 3).
It seems that the power is expanding not only in Chuo-ku, but also in Chiyoda-ku, Minato-ku, Shinjuku-ku, Shibuya-ku, etc. recently, but I noticed
two or three years ago ... .
I saw it quite often in Ginza and Nihonbashi neighborhoods.
And they choose a place that is 
not so noticeable whether they want people to see it or just a mischief. For example, behind the phone in the telephone box as described above, behind the historical site display version, pillar of traffic sign, etc. ...
This is the
back of the historical site explanation version in front of 
Hotel Villa Fontaine at Eitai-dori St., Shinkawa 1-chome intersection.)
What's more, rude but clear, it's a seal with two faces, "eerie" that I don't think it's cute or wonderful 
at all.
When, who, for what, and for me, I was wondering what ...
It seems that it has become a common topic in recent years.
When I searched variously on a personal computer, there were many people who were more interested than me, such as me, so 
it was very easy to understand and detailed, so I put an address.
“Ginza Spy Research Office”: http://ameblo.jp/ginza-spy/theme5-10010258982.html#main
“Tongariyama” ... http://tongariyama.kyo2.jp/c7661.html
It seems that the author of the "Rikishi Seal" has also been narrowed down. I look forward to the future.
