Why is it that when it comes to monsters in general and the undead in particular, Japan just can't seem to maintain any sort of naming / form consistency? They'll just grab whatever name suits their fancy and throw them around freely with no regard for what the words actually mean.
Lento turns into a zombie and gets called a ghoul. He then turns into a ghoul and gets called a zombie (then briefly a thrall, then back to zombie). And then he becomes a vampire that is, in classic Japanese manner, completely impervious to sunlight and has ugly mini-wings. He might as well be an incubus.
And to make matters worse, the NRBL translators keep calling him "Rentt", which is ridiculous no matter how you look at it. The Japanese language can't even end a word with one "t", let alone two. Can't they just use the existing name translation? Is it like some kind of translator in-joke to keep fucking around with names to cause deliberate confusion?
Anyway, there is no real plot to speak of. It isn't an isekai, but it might as well be as it reads similarly enough.
Bad series. Have a 4/10.