you can get this card at “tourist information center” in front of Shibamata Station.
There are some manhole around Shinkoiwa station.
This is a dam card of “Lake Saiko”
I got this card when I visited Lake saiko.
you can get this as free.
“Ministry of Land, Infrastructure and Transport”
for more information to get dam card of lake saiko
There is a 20th anniversary card this year.
You can get anniversary card,too at same time this year!!