Before the book hit the shelves, there was a flood of around 400 000 pre-orders for the book. 430 000 books were printed and a reprint will be taking place soon.
It looks like "KAGEROU" is set to become a best-selling novel! (Mainichi)
Buy the book online here.
Maybe it's just me, but as a non-Japanese speaker I can't stop typing "KANGEROU".