In a way, this manga uses the concept of eroticism. The sexualization that they did in Usum is intentionally uncomfortable because he is something different and people's reaction will be different, this story is exploring some intricate concept, that i will admit is a little too much for me to try to discourse, my english is lacking for that.
Personally, it doesn't affect me, if done right and here it is, i can deal with pretty much anything.