Point one which must be addressed
*youkai: A term that describes any kind of supernatural being. Demons, vampires, angels, spirits are all various kinds of youkai.
In English, supernatural is the umbrella term. The words demon(Daemon), vampire, angel and spirit are our ways of trying to describe the creature further.
For example, a demon is something purely evil, perhaps connected with Satan or his counterpart in whatever religion you subscribe to, a vampire is a parasite of some sort, an angel is a benevolent force, the counterpart of a demon, and spirits are presences of an unknown nature.
Introducing a random umbrella term for them, 'youkai' is redundant.
We already have a term describing supernaturals.
In English speaking dialects, the sound of the word youkai, presuming I'm pronouncing it right, is completely off kilter. Youkai is a pleasant sounding word to our ears, almost like a nick name you might give to someone. Not very appropriate considering that supernaturals are inherently unknown, mysterious and implicitly dangerous.
The only way it would possibly make sense to use the term youkai, is if we were all Japanese, or if the RPG was intrinsically linked to Japan. Which I have my doubts about, seeing as it's based in a geyser in yellowstone park.
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Ok that was just a rant about lifting inappropriate words into English.
Onto the more serious business.
So a big *** rift in space and time appears. Ok, I can get behind that.
So they decide to deploy a science team and make contact immediately? Wouldn't it make more sense to start small? Get a team inside the rift, make sure the place isn't completely and utterly poisonous, that kind of stuff. Learn more about what they've found before they decide to charge in and rattle cages?
To that end, why send a team when they could send in another robotic vehicle? it's 2017 for gods sake.
Also, CS, they're obviously not sending hobos in, they're going to send scientists.
What would a bullet do to a demon?
Depends on what the demon is made of. If it's a spirit, nothing. We don't have weapons for fighting spirits, because for all practical intents and purposes, there's no proof they exist.