It's a meme for the typo that the translator did lol, so he kinda became a comic invisible character
basically its a translation error the team made by translating HAVE to HAHE. Since then this has become an inside meme where they are all trying to find out and catch who HAHE is lol. They are treating HAHE as a mysterious character
this meme started back at chapter 18
LoL thanks alot guys (づ￣ ³￣)づ
What's hahe mean???