What started as a great horror story became the most boring, repetitive and stupid shonen ever. Best BBEG ever.

It started as an interesting horror manga of vampires. The island was dark and oppressive, the vampires were evil, inhuman monsters, the demons and other creatures were horrible and powerful, and the main characters suffered and tried to escape, struggling to survive in the cursed island.

And suddenly, a timeskip, and the whole manga changed. The main character had the ability to cut iron bars with a sword that it found on the trash for no apparent reason except because he was oh so strong. The vampires, established to be stronger and faster than any human at first, were easily killed now, not even a nuisance, and then the demons were also killed with ease. Even the supporting cast became also great warriors, even if they didn't had that much training, and one of them had infinite bombs for some reason. It wasn't horror anymore, it was just a dumb shonen with ridiculous power levels for absolutely no reason.

The main character changed completely. From a young kid that barely knew anything he became a powerful warrior, impossibly strong, confident and great leader. He had a Goku personality where he always wanted to fight the greatest warrior to test his strength, and no one could attack him from the back because... he had a sad back. Seriously. How can a back communicate feelings, I don't f*cking know. Oh also, he has a small problem of loss of short term memory where he can't remember some stuff, like the fact that vampires smell even a small drop of blood. Something that he forgot, two times, in less than 5 minutes, in the final battle, after fighting vampires for a year.

The story became full of plot conveniences too. The island was suddenly mutable, and it had as many cities, abandoned buildings, named forests and swamps as needed right at the moment. The main cast arrives to one of the towns and it saw that it was in bridges over a river, and suddenly it remembered that the town was called over the water, fact that was never mentioned before. They needed to go somewhere, but apparently there was a cursed forest full of monsters in the middle that no one mentioned until that moment. This repeated over and over and over, and as easy as these landmarks appeared, they disappeared too. The same happened with swords, that were everywhere for some reason, and some other stuff like vehicles.

And this also happened with characters. "Oh yes, in this town that we are basically right on the door, there was this character that was never mentioned before, that is the right hand of the main villain and that it was also a friend of your brother and a student of your master, who is also super powerful"... Right. This happened a few times too. I won't even mark it as a spoiler because as it appears, it also disappears that easily.

The story became very boring and repetitive, but when the story remembered that it was an horror story and acted as such, it was very good. This usually happened when Miyabi appeared, the Big Bad Evil Guy of the story. Honestly, the best character, he looked incredibly evil, he was incredibly evil, he was powerful and terrible, and he had reasons to be that powerful and terrible. He always had the spotlight, with that terrible grin and his inhuman intelligence and cruelty. He had a weak backstory, but I can forgive that with such a good character.

I will say a spoiler here. At the end of the manga The main character forgets how the main weakness of Miyabi works, a medicine that deactivated it's regeneration for a few moments. So he used the medicine, and when he had the chance to kill him, he just stood there, not dealing the final blow, because he acted as if the medicine was a poison. Then he remembered how the thing worked, but Miyabi reacted, escaped and battled him until the medicine passed and he recovered his powers. Because there is no more medicine, the main character wasted the possibility to kill Miyabi. Ever. Because he's an idiot.

There's a second manga with the end of the story. I stopped reading it when I saw the phrase "he has a sad back". It's the same stupid shonen but right from the start, and I knew that there would be some deus ex machina so they can defeat Miyabi. I'd rather not see how the best character in the manga is killed off by some convenient crap after the last hope of defeating him was forever lost thanks to the main character stupidity