It's rare that I admire an anime so much that I log into MAL to give it a 10/10 on everything. This is just masterful writing, and Yoshitoki Oima is an extremely talented storyteller who knows how to appeal to emotion without overdramatizing dialogue. I am happy to be born in a time that Oima is creating works.
Story: 10. It can be boiled down quite simply: An eternal being is placed on this Earth to learn and adapt from its surroundings and journeys to learn more. With such an open concept, the story relies less on plot and more on character development, which I love.
Art: 10. No complaints. Clean, fresh, simple and fits the tone of the story.
Character: 10 hands down. No unlikeable characters, complex relationships and believable dialogues, and genuine personalities that aren't just trying to fit a trope.
Enjoyment: 10. Do I enjoy crying? I guess so.