Shingeki no Kyojin: Before the Fall

A baby is found crying in a mass of Titan vomit, amidst the dead titan flames. The child is called "child of titan" and is essentially hated by the people inside the walls. He also seems to grow unnaturally fast. Named Kuklo, he parts himself from his past/upbringing and gambles on the fate of humanity by enlisting in the scouting legion.

(Source: MangaHelpers)

Shingeki no Kyojin: Before the Fall is a manga adaptation of the second and third volumes of Ryou Suzukaze's light novel series of the same title, which itself is a spin-off series of Hajime Isayama's Shingeki no Kyojin.

The series was published in English as Attack on Titan: Before the Fall by Kodansha USA from March 11, 2014, to August 27, 2019.