Wonder 3

Wonder 3 is a very good manga by Osamu Tezuka that is somewhat overshadowed by a controversy where Tezuka may have been a victim of plagiarism/industrial espionage (see https://tezukainenglish.com/wp/?page_id=1585 if you want the details). Actually based on the anime version, it apparently has a very different plot from the original. Despite featuring three talking animals, this manga comes off as one of Tezuka's more mature early works. The protagonist is Shinichi Hoshi. Though the three aliens find most humans they meet to be rotten to the core, they find Shinichi to be pure-hearted and kind. But Shinichi is a complex character. He has a goodheart, but he is so principled that he is enraged by the corruption, disingenuity, and cruelty around him. This, alongside his immaturity, leads him to constantly get into fights and constantly skip school. Thus, Shinichi is a much more complex character than other early Tezuka protagonists. Additionally, this is a relatively serious science fiction story despite being written for young boys. The three aliens are trying to find out if humanity is worth saving, so the theme explored a lot is the idea of the corruption that is inherent among much of humanity. There is a big focus on the corruption, deceit, and the other things that make humans despicable, and it's done in a relatively realistic way (at least for the time). It's also a coming-of-age story for the protagonist, Shinichi, as he learns self-control and starts to gain friends. 8/10