I am confusion explain somebody please

What are you confused about? Maybe I can explain lol

what is candy after? like why did he come to hajun in the first chapter

Yesss

Oh candy was supposed to get some blueprints from hajun, that was his original mission.

Candy's agency were trying to get blueprints from some guy, what did they didn't know is that guy has no possession of the blueprint yet because before he was gonna get possession of the blueprint, the guy (Hajun's dad) went into hiding.

So the agency did some background check on that person and they believe before the guy went into hiding he gave the blueprints to his son, hajun.

Basically candy was supposed to make hajun trust him enough to tell about the blueprint

So yeah everytime candy says "this is just my mission" he meant its just his mission to make hajun trust him ╮(￣▽￣)╭

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