Although not written by Isayama Hajime this is a story that is considered part of the Attack on Titan canon (according to my research). I know you asked this question back in 2017 and probably know the answer by now (if you’re still wondering, you really need to develop your research skills) and you might not even use Mangago any more. But I figured I would answer so that it would be viewable by others like us who have the same question.
is this canon? wtf it's 2017 how come i didnt know abt this