1) The current people of this era doesn't know they do that. They just know its a hated race. Why? I assume it's because during a reset the dark races take over and kill off the light races. Not many live to tell the tale once the reset happens again. and if they do, they will know that the reset is inevitable.
2) They don't know he's of the hated race. Only a human that has some special powers that's totally useless (for their standard) because he just stepped into this world. So as the 'seniors' in this side of the world they help him get better. (it's a school after all and classmates/children don't think so far)
3) *extra treat* The reason why the race didn't die off when they're being hunted to extinction that one time is because for some reason, their tribe form a very unique bond with elven races. No idea why but its natural. (which is why MC has senior~ the current patriarch has a female elf?fiancee? by his side) So the elven races(not all, but there's one that always comes up: Elves from The Forest of Fireflies.) shelter them during those times. (extra note: The elves from that forest go to the other school that the cousin/patriarch go to as well.) I forgot why they didn't put the MC there too. Think it's still because they didn't want him to know about the tribe.
If you've read the translated chapters so far, Andier(or what the translator first translated as Andellar) is ranked No.1 Fighter of the Ghost King Yelu. He's a double robe holder of Black/Blue meaning he's from the Phoenix clan and traitor to all the light races. I guess you could say he's the greatest antagonist to MC and Senior apart from the other Ghost Kings. He's extremely strong and cunning, tricking the MC time again and again. Even Senior can't win against him for that matter. So, Senior is the son of the 3rd prince of the Ice Fang Clan and MC is the descendant of the Yaoshi. What's the link? Andier is actually a 'close?' friend of those two. (Which is also why he likes picking on the MC and Senior quite abit) He's the one that killed/started the Yaoshi massacre, leading to the ancestor of the MC to turn bad and start to ally with the dark races during the war hundreds of years ago. To combat that, Senior's dad had to lead an army to quell the war and in doing so, led to a fight between those two friends due to Andier. (It was all a misunderstanding really...but there were deaths so neither could back out from it.) According to my (shoddy) memory, that's how it went, which is why I absolutely hate Andier very much. But I admit he's mighty fine and glamorous.
Hahhaa, close enough! I see the book cover, its as good as out. Half sad that it'll be the final season.. I really like their journey so much. Can't find the raws for S2 and its 2nd part.. aaaaa