Lin En is reincarnated into a medieval villager, just in time for a goblin invasion of the village. Thinking he is doomed from the start, he discovers that after killing a goblin, a "Monster Appraisal Handbook" appears in his mind. As long as he kills monsters, he can obtain corresponding bloodline points, unlock monster bloodlines, and enhance himself. From mutant goblins and lava behemoths to chromatic dragons, collecting various monster bloodlines unlocks goblin stealth, slime mimicry, and dragon breath. So what if I have a few more monster bloodlines in my body? On what grounds do you say I am not human!