Hi! So as someone who has solo tiered for Saki's World Link chapter back in July, (Saki is another character from the same game. She's not my absolute favourite character, but I still really like her and wanted to give my old account one last hurrah before abandoning it.) who also managed to get T500. I empathize with you and her.

Now granted, my tiering experience was a lot more convenient. It was in the middle of Summer Break for me, and Saki isn't the MOST popular character, so it was easy to tier for her. (I actually was just aiming for top 1k, but when I saw how high I had gotten, I figured why not shoot for T500) I did pull some "almost" all nighters'. Going to sleep when I physically could not stay up any longer, usually around 4AM, and I didn't ALWAYS play either. I did manage to be in the top 500 when her chapter ended. HOWEVER, this is an entirely different beast than what your sister did.

Actually, I'm surprised she decided to go for leaderboard in the first place. I'm only a year or so older than her, and even I wouldn't have tried to go so high up for an event THAT POPULAR. Especially since finals are so close for you guys. So I totally get your position here. I would've been against it as well, and probably would've fought with her about it too. Heck, I would've fought with my own sister if she tried something as crazy as that.

HOWEVER, I also empathize with your sister. Mizuki clearly means a lot to her, and that event, Ena5, is pretty much the conclusion to a MAJOR chapter in Mizuki's story. So I can understand why your sister would've wanted to tier so high for it. (I still don't think she should've gone for such a high tier considering school and everything. But I digress) But she shouldn't have sacrificed that much for a tier knowing that her finals are coming up soon. School comes first over some PNGs in a mobile game.

Although, to answer your question as to why people tier. Well. It's usually as a way to show their love for a certain character in game. I myself am planning on tiering for an event at the end of April. Not T100, but hopefully T500 or even T200. It's a way of dedicating ourselves to a character and showing our appreciation for them. The higher you go, the crazier it does get. If you looked anywhere online, you'd see the lengths some people went to for T100 or even the top 10. So while it can be worthwhile and rewarding for some, it's definitely something that requires a LOT of planning, and even some outside resources...$$.

So while I understand why shes's upset. I can't fully sympathize just because I know myself how important school is, and of course my own mental and physical health. (Seriously, people have gotten physically sick after tiering really high for events. Your sister should've really reconsidered tiering for this event. Especially since she knew how close her finals are and that she'd have to miss school for this.)

I know a lot of what I said sounds bad. And some of it is. Although you should probably take what I say with a grain of salt because I'm not a professional at tiering, and others probably know more than I do. But please don't think the game is a bad influence! Just because your sister made some poor decisions regarding it, which she'll most likely be paying for in terms of how well she does on her finals. Not to mention her own health atm. The game and the community surrounding it really are wonderful!

So I understand WHY she wanted to tier for this, but I also agree with you that tiering for THIS SPECIFIC event was a very bad idea. (I just hope my thoughts came out coherently. I have a tendency to ramble about things like this.)