The Terminally Ill Young Master is the Mad Dog of the Underworld

When Allen Vert, the terminally ill heir of a noble family, awoke from a fever, he realized he was the reincarnation of Karzan, the mad dog who once roamed the Underworld.
… But something was definitely off with this household.
“Allen, every noble needs secrets and shadows.”
The sinister and chilling schemes of his older brother tightened around him, layer by layer.
“Lately, I hear you’ve been up to some interesting things.”
The watchful eyes and ears of the powerful family head lurked everywhere, keeping tabs on his every move.
“… When am I going to see Mother?”
It felt like a distant dream to meet his mother who withdrew into isolation due to a mental illness.
‘But that’s fine.’
Karzan may have failed, but Allen Vert’s path is just beginning.
“Two lives, two revenges.”
No mercy.
I’ll pay it all back—with interest.