Ash Grim Reaper and Immortal Cat

The boy knew. The meaning of taking a life. Why did you become immortal?

In an era when the concept of a god of death did not exist yet, the boy Gat was
aiming to become a full-fledged assassin in the maritime nation “Enetia”.

One day he was scolded for not being able to kill him as usual, he
met the strange appearance of his longing senior and a strange person who claims to be a god of death.
Master-slave dark fantasy starts!