The mysterious undead ( oc x the seraph of the end)🪽

It's only a sudden inspiration I had in mind for a while, if Mika had met someone other than Krul who treats him like his own son? And gain an adoptive family? But the man was not a vampire or human, but an undead. How would he change its original story? watch this and find out. P.S there will be multi crossover so I hope you won't be angry by it.