COMRADE!Onee-san camp superiority.
Just because people in other worlds regularly kidnap/summon people doesn’t mean they all do. It’s a world with its own logic, and within its own logic it’s a far flung story.Above all, it is a world of magic, so they shouldn't find the idea so impossible. In our universe it would sound stupid, but that's because we don't have magic.
But their relationship become closer after cup of blood. So it's blood related little sister.that's a free non blood related little sister
Let's say you met a Roswell Grey who told you that he/she/whatever came from outside of our Solar System and to demonstrate you some nice tech, the creature would fire a few clean holes in a nearby rock with a raygun. Would you still tell the Grey that, nah, you don't believe in aliens, so the thing must be some weird mutated monkey instead. The raygun you would just explain to be light from Venus reflected by swamp gas.Just because people in other worlds regularly kidnap/summon people doesn’t mean they all do. It’s a world with its own logic, and within its own logic it’s a far flung story.