Is the sister going to be something?

Nah... she ain't treated like sht... she just gets what she deserves... like... her misfortunes are from her own doing not someone deliberately messing with her... maybe you'll find off-putting but honestly? It's nice to see someone selfish and malicious getting their due... I don't think she'll become a real threat in the future cuz the only reason she got strong on 1st life was mc's nurturing...

Tru. She just makes bad life choices and overall a nasty human being so this is the life she made with her own hands.

She just never takes the time to actually learn to use her class. I'm sure she'll be killed off in no time.

I agree she diserved everything shes getting, what i'm trying to say is I don't find her suffering entertaining or funny. Like for me she's meaningless to the story so take her out already if the MC doesn't care than neither do I. It's sort of backwards to say the mc doesn't care but keep showing her if we are not suppose to care.

Yeah I get your point... I think it's more to reinforce to us readers that he really is the only reason she got so far in the first life. I understand you don't care... but think of it in another way... she showing up so much shows that deep down mc do cares... after all how could he not when she betrayed him like that? With his personality if he really didn't care he wouldn't even notice it was her. So even if not explicitly it does show that mc is enjoying seeing her get screwed over again and again... not only it alleviates his pain of being betrayed like that but it's also a kind of reminder to mc that he is doing the right thing and walking the right path this time. Otherwise mc would've just offed her like he did with the idol guy.
She ain't as meaningless as you think because she's the main reason everything happened... besides... I guess there'll be a point where mc will come clean about his identity and off her properly to get a closure on his revenge... but that's my guess...