THIS SHOULD NOT BE CONSIDERED CANNON TO ANY PLANS. THIS IS JUST MY GENERAL OPINION, EXPLORATION ON WHAT KIND OF PEOPLE RIVALS 9 AND 10 WILL BE, AND A THEORY ON HOW THINGS WILL PLAY OUT.
PLEASE PROCEED BELOW
My thing on Hanako and Megami is that they're not exactly love rivals, but more people in the way. (This comes from Osoro being the last person to have a noticable yet leany crush on Taro)
Hanako is Taro's little sister. She's gonna be a person who won't let Ayano spend quality time with him, because she'll take up all his attention. I.e. maybe she'll interrupt the confession scene and drag Taro home. Idfk
Megami is the school's top student (and plus her family owns the biggest company in the game). So of course Taro would believe her if she said "Senpai I think there might be someone stalking you!" (Yes I got that from the rival introduction video.) But wait... How is she going to prove that?
I believe on the 10th week. (or during the weekend of week 9) Megami is going to march up to the "info room" with her father and grandfather, and get info Chan out. This event will possibly be what makes it challenging. Because Ayano doesn't have Info's help anymore. She's on her own. Now, Info Chan being the woman she is, would probably already know something like that is going to happen. So she puts the info on flash drive, and deletes the videos (but not all of them by accident). Once out, Megami investigates what has been done and finds out what has happened so far.
Thus pinpointing Taro's stalker. While this is happening, Info Chan asks Ayano for a huge favor. One that would repay all the favors she's done for Ayano. And that is too get Megami out of the info room, and Info Chan back in.