Monster Skin - 6

An old apartment in the center of Prague with a sign saying Three Frogs...
A woman who lived there with her twin children about ten years ago... Tenma learns about this from his old neighbors. They also tell him about the Czechoslovak Secret Service and a suspicious fire.
Could those twins be Johan and Anna? On the other hand, Suk, a young detective in the Prague police, is very impressed by the beautiful girl he meets in the bar. The girl's name is Anna! When Tenma and Suk meet, they have no idea that another horror is sneaking up on them!
BKA's chief detective Lunge is finally convinced that Johan is involved in the serial murders. He comes to Prague to find out exactly what happened to Johan and learns that the mysterious illustrated storybook called "The Nameless Monster", which deeply affected Johan's childhood, was actually written by a Czechoslovak Secret Service agent. Lunge goes to the location called "Rose Mansion", which the author used to write the book, and there, he discovers an old door in a wall covered with plaster!
Behind this door, truly terrifying things will unfold!