so basically this is assassination classroom it's like an another dimension type so basically you and the others are demon hunters you hunt and get reward so basically koro sensei is known as an unbeatable demon and you(your name is yuki) and karma, nagisa, kayano, yuri(your little sister),you will get the imperial black blade which is an earing with a sword and solid red ribbon on it when you flick it, it will transform as a weapon you think of, karma gets the flame sword it's a ring, nagisa gets a very strong blue sword it's a badge, and kayano gets a green sword used like a want to use magic it's a bracelet and yuri gets a necklace which js the light sword