@KoL I'd at least like @AgentFallenSoul to tell myself what rubs him/her wrong though :c, not for the sake of discussion, I couldn't care less, but it irks me a bit that you have to play the messenger and then I don't even get to know the exact reasons.
Also I got a few questions in regards to a thing I think I am going for, which is kind of an innocent devil archetype I guess:
Is the Crimson Sky only in a specific region(Japan) or does it include the entire world? If later is the case, are those Chaser people and agencies and stuff in Japan or on a more global level? How does Japan compare to the rest of the world/Crimson Sky? Please don't decide for "only Japan" now just because of those (annoying?) questions though!
I understood right that the Crimson Sky is only enterable for humans at night but Youkai can go as there please? Or do Youkai have no "easy" access to the "real world"? Or I guess they can just change between those two places at night too @-@?
I am going to read the big text about Youkai in a minute that you wrote in the interest check, so if that question is answered there don't bother explaining, I just want to get this out quick because the sooner my questions are out of the way the sooner I can work on a new sheet! How are Youkai's born? Simple smex? Or myth stuff too (Like objects becoming alive and stuff)?
How prone are you for eldritch-kind of things? Like, a person who summons stuff from "another plane" that is not classified as a Youkai would mean that there is even more "unknown" even if it is just for the sake of fluff (I am not going for a summoner, well, at least not in a direct sense)?
I understand your point with Agent, so I'll let her explain it.
Now for your other questions.
Both the Crimson Sky and the Chasers are a global thing. The name Youkai is used mostly on Japan, though, on other places they would call the denizens of the red realm Monsters, Fairies or even Aliens.
The passages are available only during the night (or on very special other circumstances), for everyone, human and Youkai alike. So, if an Youkai comes to the human world and don't leave until the morning it's locked here until the next nightfall. To being like vampires this can be lethal.
This depends on the type of Youkai. There are all kinds of legends out there, and most of them are at least partially real. Some of them are ven created from humans who got corrupted by the essence of the Crimson Sky and turned into monsters.
Well, I really don't care much to your character's origins if you wanna know. As long as it makes sense. That said, eldritch/divine/interdimensional & stuff is mostly the prerogative of the GMs as NPCs, unless you give us a very well written character. Remember that the Youkai are broad enough that you probably don't need this to create whatever you may be thinking.