Who knows... maybe that human realized what's Purupuru's true form, and still wants to protect him. Or maybe he's also a monster fooling another monster... Or maybe he's fooled by PuruČ powers, and actually think he's protecting another human... The creature doesn't have his rape face on like in the previous pics I've made of him, so I guess that guy's not gonna get devoured... yet. :I
Purupuru usually preys on a human being, appearing to him as a normal person, while messing up with his senses and altering his perception of the reality (if you ever played/watched Saya no Uta, it's kind of the same deal).
The paper on his face works a little like the leaf Tanukis use to change their shape. Except he doesn't actually change his shape, but appears to humans as a normal person as long as he got it on his face.