Going off the Shout-Out section in the main page, it looks like Celestial Warrior Moon will be making numerous crossovers with The Slender Man Mythos.It would make perfect sense. The Land of Black Leaves is pretty much Robert's The Path of Black Leaves. And The Rake has made an appearance and Dr. Corenthal has been mentioned. Really, all the framework for has been put in place.
Sailor Pluto will be a Time LordWhy not? She time travels and Luna's also had an encounter with a Weeping Angel.
Wakagi's antic are going to result in The Unmasqued WorldInspector Wakagi is a law enforcer thoroughly frustrated with Inspector Ishida's/ Artemis covering up of the truth surrounding the strange incidents happening all over the country and has recently been seen stealing the corpses of monsters from crime scenes and video taped a teleportation. These actions will lead to The Keepers being exposed to the world at large.
The Senshi/Warriors will have another run-in with The RakeEven though The Rake currently can't get back to Japan, it's already been established that the girls can go on missions to other countries. So chances are if he starts causing trouble again, they'll be sent to deal with him.
The Celestial Warriors' Transformations have a horrifying secret.Think about Buffy being the Slayer. It could be something similar, but worse.
The Seven Great YoumaSupposedly they're all going to be the same people, but in cannon one of them was a nameless priest and the other was a cat. Gotta guess they're going to be a bit more personal, right? Also, the seven have obviously been re-imagined, judging by Gesen->Entomon. Maybe Bokushi will be like a weeping angel or a nephilim? And with all the horror showing up, maybe there'll be a NGE shout out. Buried at the poles, trying to wipe out humanity, powerful monster children...doesn't The Entity sound a little like ADAM?
The Masked Man from Chapter 25 is ChristianChristian is a young man that was abducted by Slender Man in an earlier chapter. When he tries to kidnap Christian's girlfriend, Jenn, the latter notes that he's tall and thinly built, not unlike Christian. Well, in accordance with th Slendy's usual, many of the people who get taken by him reappear later either completely under his control or having otherwise gone insane.