I prefer Aya Azuma to Moe Harukawa, but it's not a very significant difference to me. I liked Makoto Hirasaka too. He was very well suited to the Three Fairies series. But Aya and Moe are extremely competent and, it seems to me, the most well rounded of the regulars. alphes was fine for what he was. He didn't need to do much more than that. Until HM, anyway. No idea what happened there since his art from not long before that looked a lot better. Aki Eda just couldn't draw emotion and action scenes for the life of her. She has like 3-4 faces. She did fine with the slice of life, at least.
If we get a returning character to go with the rumors, I see Sanae, Reisen, Komachi, Kaguya, Yukari, Kogasa, Nue, Suika, Seija, and Seiga as the greatest possibilities. I know I'm casting a wide net. Anyway, Sanae and Reisen are being thrust back into the spotlight, though I can't really see a way to tie them in, especially in a potentially penultimate character role, though I still see greater reason for them to be involved than Sakuya. Komachi (Or Eiki? That would be cool) *could* be interested in this type of incident. Kaguya has the Mokou connection. Yukari often has an interest in incidents or could be an instigator (she brought in the hobgoblins, after all). The rest are known as mischievous tricksters or who have been known to incorporate urban legend imagery who could be tied to the incident. But at least in the case of Seija, who has the Shinmyoumaru connection, I think another game could be a little much. Seiga is a bit of wishful thinking, but she does have a match plotwise in Kasen.
Thinking about it now, it'd be pretty cool to see yuugi duke it out
Her title is "The So-Called Unexplainable Phenomenon" and her power is to wield unexplainable phenomena (whatever that means) so I won't put her out of speculation completely
Thats a char I'd definitely love to see actualized
Well, this is kind of a mistranslation, as I recall. We've never actually seen her do anything with her power, which is based on an idiom by Confucius, or something, and has a rather simplified translation. It would be awesome if she showed up, of course. Maybe she wants to draw Kasen out? But based on what she's done, her power is seemingly only there to explain her unexplainable strength, since just saying "Strength" is rather boring. That's not to say she couldn't receive further development. I would love to see her, but I just don't think it's too likely.