Attack On Titan: Before The Fall 6

ON THE SHOULDERS OF TITANS
Fifteen years ago, humanity led a last-ditch attempt to discover the Titans'' weakness – a survey expedition to capture one of the beasts. But the ten-meter Titan who appeared during the capture attempt threw the expedition into chaos. Among those who escaped behind Wall Maria was the genius craftsman Angel, a weapon-developer who was participating in the expedition as a researcher. What would he conjure up from this failure?