Shingeki no Kyojin - Before the Fall

Set 70 years before the beginning of the manga. A baby is found crying in a mass of Titan vomit, amidst the dead titan flames. The child is known as "The Child of Titans", and is essentially hated by the people inside the walls. He also seems to grow unnaturally fast. Named Kyukuro, he parts himself from his past/upbringing and gambles on the fate of humanity by enlisting in the scouting legion.