I came here to hunt some Rin/Sheimi/Yukio scenes for a friend who watched the anime but wants me to spoil everything in the manga for her (she loves watching those three interact and ships RinxSheimi but isn't a manga person), and I got so engrossed in reading the arguments that I just had to comment.
A lot of what was said is surprising me a lot. I'm just going to comment my own opinion on some of these pairings.
Note though, romance is my least favourite genre and I actually prefer not to ship anybody with anything. This manga is actually the only one that has gotten me mildly interested in the pairings because the characters and interactions are so well done!
RinxSheimi -- Like most people, I wish this didn't happen because it's so obvious, but I can also see it being the most likely pairing mainly because of a few things. Firstly, it's the pairing that has been actively given the most attention by the author, and has had the most blatant statements on. Secondly, the author has clearly stated that Sheimi will mature more and more as the manga progresses, and by the end of it she'll be a completely different person. Maturing might also include her romantic awareness. Also, Rin is the protagonist and obviously has HUGE feelings for Sheimi so I feel like the author might feel the need to put some justice for Rin? Finally, I feel like Sheimi will be a used as a HUGE plot device for Rin later on, especially because he has so many feelings for her, and she might be necessary for him to like, do something to save her or something? He feels more affection for her than he does for anyone in the cram school.
Also, I feel like if it came down to it, he'd save Sheimi over his own brother. (Probably male-protectiveness, feeling like Yukio can protect himself, and he seems closer to her).
YukioxSheimi -- Can't see it happening. I see it being used to show both their developments as characters, but not developing the relationship. Ah, that was worded weirdly...basically, they both started the series having huge admiration for each other (someone put it nicely. Yukio sees a beautiful pure girl, and Sheimi sees a perfect genius). Now, as the series progresses and Rin gets involved, we see this initial "romance" being broken. Sheimi is seeing Yukio's flaws more and more, and Yukio is now actively backing away. He has stated a few times that she "probably doesn't have any other intentions" and stuff. Also, it seems like the only way she is good for him is occasionally making him at peace. He likes talking to her and interacting with her, and spending time with her, but like...as a person, not a girlfriend. She keeps him at peace short-term. With Rin, she can hug him and tell him it's all right, and it will affect Rin. Yukio? He won't let anyone close to him. If he broods, someone like Shura can slap him back into place.
Which brings me to my next one,
YukioxShura -- Nope. Brother/Sister, definitely. Never once has he shown any sigh of romantic intent, let alone affection. Shura shows mother-hen concern.
Actually I think Yukio will go bachelor, haha, until the end of the series. Pairing him with someone will take another series in itself, let alone everything we still have to go through to fix him (inferiority complex, self-loathing, burdens, demon taunts, etc.).
IzumoxShima,
IzumoxBon and
Izumo/Rin -- I'll talk about these together. Izumo is a hard shell to crack. If you look at all her interactions with everyone, she has fought with most people in the series (perks of being a tsundere?). The only person she has given what seems like romantic intent to is Rin. If she felt any affection for Bon or Shima, she would probably soften up a bit for them. She clearly softens up when she starts to like someone (Paku? Sheimi? Rin?), and her shell is extra-hard when she interacts with Shima and Bon. So though not necessarily romantic, she does soften up for Rin a bit, most likely because he is so genuine with her. Same with Sheimi, though that took some effort. But Shima is not genuine at ALLLLLLLLLLLL (SHIMAAAAAAAAAAAAA) and Bon's rough side irritates her sometimes (though she doesn't hate him, I don't think). So if anything, RinxIzumo is most likely (though one-sided, definitely) and the other two I would never give a thought to (funny as they are).
But really, all these statements I'm making I don't feel very strongly about, I'm just making statements out of the blue here
That's all I'll comment on for now, got to go do something. Woah that's still a long response considering how much I don't like romance. Oh well. My two-cents.
