Hajime Isayama

Worked in an internet cafe and was rejected by one of the major manga magazines before Kodansha took a chance on an art style that established editors thought too rough.

Attack on Titan puts the last of humanity inside three concentric walls, besieged by giants that eat people for no discernible reason, and then spends a decade revealing that almost every assumption in that sentence is wrong.

The later arcs turn into a study of nationalism, inherited grievance and mass violence, and the ending divided readers permanently. Isayama has said he was thinking about the Japanese island of Hokkaido and about being the person outside the wall.