A whole lot happens in this arc, and by that I mean a whole lot of nothing till the end.
This is probably my least favorite arc to be honest.
We meet Lancia who is kinda relevant Later…we meet Chikusa who is kinda just there we meet M.M. who will not reappear for like ever until she just hops into the frame at the tail end of the anime and we meet Ken the resident Tsundere who apparently has a thing for the best girl but doesn't wanna admit it.
Oh somewhere before we also met Bianchi … Gokuderas Sister … I didn't really realize that she was there most of the time which is pretty sad.
The only thing that REALLY was relevant in this arc to be honest is that Tsuna finally got his weapon but I woudln't call it a real arc because of that.