So, this is actually a long running story called "My Vampire System." I just spoke with the author and he said that this is the pirated Chinese version. He's requested that everyone read it on official channels to garner support in hopes that it someday is made into an anime
For that preview at the end, whoever the author is really needs to do their research before they just give things names things. That gun shown is not a Glock, it's a 1911. Glock (a gun company) does not make 1911's.