The Wanted Assassins

There is a world where war is happening between two race. The Heaven Race and the Underworld Race.
The Heaven Race consists of five clans. They build alliance with each other just to defeat the Underworld Race. But in the end, Underworld Race still over powered them.
Each leader of five clans defeated but managed to escape death. They promise that they will back in this world and take their revenge.
After leaving their own world, they decided to go to another world who is far away from their world and that is the Mortal World, that cause them to become a spirits and it limits their power.
The Mortal World where in there is a group of assassins who are wanted in this place. What will happen if the leader of each five clans meet the notorious and wanted assassins in Mortal World? What will they planning to do? What will be their life after meeting each other?