@Hydraguard first of all, Mc is still a child, he may be mature for his age but he is just a teen who was just chilling in high-school assainating HUMANS not whole a** demons, SECOND OF ALL did you read with you eyes closed? He tried to slice at the demons neck but the demon jumped away leading him to only slice his shoulder, we are not reading a one-shot op Mc, he's a child who has to grow more powerful, it would be boring if the HIGH RANKING DEMON was ended there, there would be no growth and we wouldn't see him develop a skill to move faster, and he also mention he wanted th demon to summon his allies so they could be killed easier....please read the story before you complain
Encrid's wife (*⌒3⌒*) 
Spoiler!
I'm 16 hehe :3