Because of the deal his father made with demons, Hyakkimaru was born with no organs. He had no skin, none of his five senses, and no limbs but thanks to a timely meeting with a doctor who manufactured artificial limbs, he was able to survive for many years. Jukai, the doctor, knowing that Hyakkimaru had the challenging task of hunting down demons, armed him with blades connected to his elbows. Furthermore, despite being blind, he’s still able to see the souls of people and to tell a demon apart from a normal person. The lack of organs has made Hyakkimaru deadly and the return of them seems to subdue that.

Due to his lack of organs, Hyakkimaru has never learned to speak or read, he’s never heard a single word and never smelled a single scent. Those disabilities have also prevented him from getting the same sort of education that an ordinary child, even a homeless one, would get. As he gains his senses, Hyakkimaru is starting to gain all the experiences one would normally have as a baby. This doesn’t just extend to his senses but also his moral compass. He must learn what’s right or wrong.

Hyakkimaru grew up only having one real direction: if he sees red, he must attack. He really didn’t have any other purpose than that and it solely dictated his every action. Initially, he isn’t really a hero and probably would have left Dororo to be assaulted by bandits if a demon hadn’t popped up. Furthermore, we see his aggressive demon-slaying behavior lead to the death of Mio and the children she was taken care of because his thoughts were only concerned with slaying a demon he’d recently lost a leg to.

Despite the limited connection he’s been able to make with people, there’s still a great sensitivity to the way Hyakkimaru behaves with others. He’s shown with Jukai, Dororo, and Mio that he can empathize with their suffering and pain by touching their faces. We also see him truly express emotion when Mio is killed by soldiers and he loses his composure. With every sense Hyakkimaru gains back from slaying demons, we’re getting closer to seeing someone who cares deeply for the people he gets attached to.

As he gains his senses, learns the meaning of fear and pain, and starts to gain a greater connection with the people around him, Hyakkimaru is learning to grow beyond this one-dimensional mindset of constant assault on demons. He goes as far as to spare a demon who had fallen in love with a villager. It isn’t all positive as we see when Mio is killed; Hyakkimaru loses his cool and we see him murder humans for the first time. It takes Dororo to stop him from killing the last person standing and regain his composure.