Well technically the stuff he going over are part of an engineer degree but we don't really have a full backstory to his life... Yet.. ... I forgot if they say it in adaption or not but he did have alot of trial and error to even make blackpowder weapons
@aosuki well, just think of it this way. He came out of no where and claim all those monster r his kills. So it reasonable to give him a little test to see his strength if he was true or he stole all those monster from someone else.
@Kampfarsch
Well she didn't hurt(kill) the guy, she only split him into 2 good n bad and imprisoned the bad part. They only mention hurt, but nothing about keeping them in cage.
@Pachka84 the author ment her body can easily live for that long but her mind that if normal earthling can't really handle 300 years of experience. The 5k figure is if she decide to be with the demons lord otherwise it will be around 300 with her mana cap if she decide to stay in that world...
Okay minor divination from the ln. In the ln, the monster after first floor should be undead related mob which instead of fighting our Boi they instead open up a path unhindered for him to go through because you know... Death attraction attribute... ¯\_(ツ)_/¯
Still liking this manga so far