Dipping my toes into the sea of manga: Drifters by Kohta Hirano
Ok, I get the first part - warriors are being pulled into this alternate world, this particular warrior is a Japanese samurai (despite what appears to be to be historically inaccurate details and behavior). Strange world, elf-like creatures, mysterious powers....and then everything went nuts. Different mysterious powers, different people killing other people, or maybe they're the same people and...I don't get it. And that guy does NOT look 30.