With Hakumyu currently running in the theatre and the current cast being active on twitter, there have been some clues flying around who's next with standing in the centre of attention and being recipient of Chizuru's affection.
There are categories to chances:
1. Cast members popularity
2. After a HijiHen a 〇〇Hen always followed
3. Routes that haven't been done yet
4. Spoilers/ character gets a spotlight with Chizuru in the current show
Within these categories are:
1) OkiHen, TouHen, KazaHen
2)KazaHen
3) IbaHen, SakaHen
4) (under the cut)
KazaHen appearing twice doesn't mean he has that much of an advantage over the others.
I personally think that IbaHen and SakaHen are currently the most likely. Even though OkiHen and TouHen aren't unlikely either considering how popular Kento and Yuta became.
KazaHen's possiblity is quite high, too, due to Sasaki Yoshihide's popularity and himself posting on twitter in a cryptic way he wants to do KazaHen.
4) again Heisuke Hen, maybe Yamazaki Hen as well (as he gets a harmonised song with Chizuru for the first time), maybe in the near future but not necessarily next year Nagakura Hen.
Let's play "Guess what" for Shinkai Hijikata Hen, while we wait for it to come:
New songs or old songs revised?
Mouri and Sakabe haven't yet cooperated, will they reuse songs from the Nishida era? I highly doubt that they will reuse a majority, this gives Mouri a greater freedom to create a script that's really his. I'm sure he will draw inspiration from Nishida, but at since he's the father of Hakumyu, you know?
Good ending or bad ending?
Hard to say, there's one play twice and one play not his route by name. I, of course, hope there'll be a good ending for Kubohide. They might go with a similar strategy as Collar X Malice did and have one evening a good ending and one evening a bad ending.
Guest talk?
I think it's highly likely. Considering that almost all former Hijikata-actors are still actively connected to Hakumyu. This includes Yazaki, Gaku and Izawa. (Sasahide will be there, too of course.) Maybe we get lucky and a former HijiChizuru appears, but I don't have high hopes for that, since none of them is really active in the acting business. Mika lives in Kochi Prefecture on top of that.
Personal hopes?
I hope the songs for Chizuru are good and let Ruri shine in her profession as traditional singer. Maybe they can even use them as a BGM even, when the scene of going to Ezo comes (she is born in Hokkaido and has sung old Hokkaidoer songs before)
My friend @koto-wari hopes for the onigiri scene to be adapted and that the former "Ore dake no yume" and "Katana ni komeyo" scenes gonna be good and be ripping our hearts apart.
And well the most essential thing has to be:
The lead dynamic: between Kubohide and Ruri
The group dynamic: between Kubohide and his friends, comrades and the Shinsengumi.
Feel free to use the comments as a room for speculations and your thoughts on the matter!
Because the post got too long, for further reading
Update:
So for the upcoming production in 2024, there are following options:
Okita
Iba
Sakamoto
Harada
Heisuke
The smaller possibilities:
Hijikata Shinkai
Kazama Shinkai
Yamazaki
Shinpachi
Not considered/surprising options:
Kitan
Reimeiroku
Why:
Okita Hen: Okita is one of the three most popular characters of Hakuouki, so considering that we had two Hijikata Hens and two Saito Hens, there's definitely a possibility.
Iba & Sakamoto: according to the muster he had right now, it could be either of these two. The only down in their possibility is that they aren't very popular routes and might be hard to adapt
Harada and Heisuke: these two routes could either get a Shitan or a Shinkai.
The smaller possibilities:
Hijikata and Kazama could always get a Shinkai Adaption looking at their popularity.
As for Shinpachi and Yamazaki: they haven't had a route yet. What makes them possible: they are closer to the story of all and probably easier to adapt. What makes them less possible: they are kinda close to Sannan as an old character new route characters.