The Slayer takes a little detour to 'Sokyo

[PROLOGUE]
Somewhere high in orbit above a demonically besieged Earth floated a magnificent castle-like space station. Its name: the Fortress of Doom, the mobile base home to an ageless warrior of legend that only the demons that now marauded the planet below feared. He went by many titles his infernal enemies had given him in his terrible campaign against their vile ilk but Doom Slayer was what he was what he was most commonly known as. And the man was busy like the Devil as he prepared for his next mission, the Slayer having just removed his artificial intelligence companion, VEGA, from the station's computer network and ceded control over to his reluctant yet necessary cyborg partner Dr. Samuel Hayden.

As the Doom Marine pocketed the device the AI had been transferred to Dr. Hayden would speak.
"Do you require anything else before we begin our journey to Urdak? You will not be able to return until the mission is complete."
The Slayer wouldn't so much as offer the scientist a grunt as he readied the Slipgate portal network to Nekravol. He had just about everything he needed to proceed. Unmaykr: acquired. VEGA: copied to that magitech floppy. Armor, health, and ammo: full. It was go-time and everyone knew it. He would put a stop to the Maykrs and their Hellish allies wicked machinations towards his people, humanity and save Earth from destruction.

Doomguy would press the rune-etched stone ball that would activate the Sentinel station's portal network. Quickly enough it would sink into the metal floor with a metallic slide, runway forming as metal arches clanked into place and a crimson-colored portal formed between the gate with a whoosh. Hefting his simple Combat Shotgun in gauntlet the Doom Slayer would charge forward and into the spatial void! Unbeknownst to the stalwart man there would be a coming "detour" that would divert the warrior from his intended destination, and take him to a whole other pocket world home to monsters of its own. Beings that would challenge a man as robust as even him, the only real indication being a slight ripple with the swirling ruby vortex that the space marine leaped through and sent him on his way.

Ready or not, the marine was coming...

[Chapter One: Not your typical Outsider]
The Slayer would pass through the tumultuous tunnel that was ubiquitous to Slipgate travel, the man utterly unphased by the flashing flight that he had made countless times now. When it finally ended as quickly as it began the space marine would make his flashy exit, and what he would find was not what he was expecting in the slightest.

Exiting the portal the Doom Slayer wouldn't find himself outside of a soul factory as expected deep within the fiery bowels of Hell, but a grassy and semi-hilly locale with a nearby forest as a backdrop. A quick look to the sky also showed that the sun was setting, the great ball of skyfire painting a picturesque sunset that splashed vibrant oranges and pinks across the clouds that dotted the space above the big man. A pleasant and cool breeze would tickle the exposed skin of his biceps, the man frowning harder than usual beneath his helmet as he glanced around this alien but admittedly beautiful landscape. Something had clearly gone wrong and Doomguy didn't know where he was beyond the fact that he was far off from his intended destination. Worse still, his attempts at reaching Dr. Hayden bore him no fruit, his Praetor Suit's communications producing [NO SIGNAL] on the corner of his HUD. Looks like it was just him and VEGA for the moment.

Shaking his head at this other unwelcome development the Doom Slayer was just starting to check his auto-map to try and at least get a bead on where he was and try to troubleshoot with VEGA when the man saw something out of the corner of his visor.

Closing his map UI the marine would focus on and find himself looking at a floating black sphere of all things, the dark ball lazily flying in his general direction. Doomguy narrowed his eyes at this unfamiliar entity as he hefted his scattergun, his guts instinct telling him to expect trouble with this thing. No Codex entries or intrusive combat tips to inform him what he might be facing here just yet, the oddball eventually coming to a halt a medium distance away from the Doom Slayer as if it noticed him. After a short pause of just hovering there the sphere would diminish to reveal something, or rather someone, the human wasn't expecting.

Standing in front of the somewhat surprised Slayer was a little girl of all things, the child a small blonde-haired kid that didn't even come up to his lower chest. The marine would give her a quick and analytical glance that told him she wasn't entirely what she appeared to be. Even more so due to the fact that she had eyes as red as ground cherry. Eyes which danced with a hunger as she in turn looked up at the larger man, a small fang poking out of the corner of her smiling mouth as she then began to speak to him.
"Oh? A human? Can I eat you? You look tougher than most Outsiders I've had."

The casual mention of victimizing humans and the threat leveled against him told the Slayer that this wasn't a regular kid. No, he was dealing with some kind of monster wearing the skin of an unassuming girl who intended to try and eat him. And he wasn't going to have it as the hulking human take aim at her with his shotgun, malicious intent of his own now burning within his eyes that produced a giggle from the girl as she stuck out her arms in a cross-pose.
"This will be fun! At least for me, human. Rumia will try to make it quick, I am hungry after all."

To that the Slayer would keep to his customary silence as he promised this creature, this "Rumia", enough lead to fill her belly and then some. Without any further preamble or witty battle taunts the scowling Slayer would explode into action and attack this T-posing fiend! A pair of Sticky Bombs would be belted out from his Combat Shotgun, flashing explosives flying and adhering to the surprised girl before detonating with terrible force. Rumia would be sent flying back several feet away with smoke trailing her scorched body, parts of her black and white dress blasted and singed from the dual explosions. She wasn't down just yet however as she shakily stood and offered the gunner a frown.
"That was awfully rude mister. I'll have to punish you for that."
Said punishment would come in the form of dozens of white orbs that erupted from the girl in a circular-pattern, twin blue-colored beams also looking to close in on the Slayer.

Even if this kind of attack was foreign to the marine he knew it was a good idea to avoid getting tagged by those projectiles and lances, the bulky and armored man bobbing and weaving with uncanny expertise that could only come from dodging projectiles from legions of demons for countless years. Sprinting backwards and with some good timing, the Slayer was able to evade the closing beams with a timely double-jump, although he still got tagged by a few white bullets. The energized impacts would cause him to let out grunts as his armor reserves fell from every blow. It wasn't anything too serious but too many of those and he would lose his protection. Rumia seemed satisfied a bit from her strikes, a smirk visible on her face as she prepared to enact another attack, only for the hasty Hellwalker to beat her to the punch.

Opting to go for overkill and end this fight quickly the Slayer would whip out his Rocket Launcher and nail Rumia with a triple-salvo via Lock-On Burst. The poor youkai wasn't expecting such a potent attack from an Outsider the trio of Argent energy infused missiles blasting the absolute Hell out of the blonde. What was left of the creature would be sent flying a short distance away, burn marks marring her form and smoke curling around her. The marine would give a small satisfied nod at the hits before rapidly making his way towards the girl were she lay smoldering.

Looming over Rumia showed that this monster had seen better days, both of her legs missing along with her right arm and the left mangled. Her once pristine blonde hair was disheveled and singed, the creature of the night hacking and coughing as her crimson eyes blearily focused on the Outsider that looked down upon her without a hint of pity.
"No fair, mister. I was just hungry. Can I at least know your name?"

To that the Doom Slayer would just glare down at her before raising his right boot and delivering a devastating stomp to the little abomination's skull, a sickening and meaty crack and splatter echoing throughout the area as the man enacted his deadly finisher. Giving the ruined remains a contemptuous twist, the now headless corpse would be left were it lay, Doomguy sparing the monstrous girl one last scowl as a small bit of health leaked from the remains before looking around the area. Nothing and no one else would see fit to accost him, the man still not having any answers to where he even was. At the very least, he did get a new Codex entry via VEGA who had quietly analyzed the brief battle between man and monster, and a monster she was. The marine would skim through the latest intel, something about Rumia being a "youkai of the dusk" being one such bit of info.

The rocket-toting Slayer would ponder upon the information his AI provided. Youkai? Weren't those creatures of Japanese myth? Again, the man would glance around his evening surroundings, still lacking in critical information. Yet he remained confident he would figure things out as always, especially with VEGA to assist him, the helpful AI speaking up.
"A peculiar situation we find ourselves in at the moment. Scans indicate that while this is Earth, it is not any location that I know of. I will do what I can to collect additional intel while also reestablishing contact with the Fortress and Dr. Hayden."

The Doom Slayer would give a grunt at that, still hefting his Rocket Launcher as he set off to nowhere in particular across the grassy and hilly lands to do some "intel gathering" of his own. He had a sneaking suspicion that he'd be encountering more things like Rumia in this place, wherever he was. But he was confident it was nothing he couldn't handle in the end. Everything died if you shot it enough, youkais included as he had just handily demonstrated to the recently departed dusk monster. He just needed the ammo for it.

If only he could toggle Infinite Ammo here...

[EXTRA]
Not far off from the retreating Outsider and the aftermath of his brutal carnage was a breach in reality, the rip hovering in the air full of unblinking eyes. Eyes which watched the oblivious Doom Slayer as he tread within the observing sage's realm, her voice speaking to herself with intrigue.
"Well, things have certainly become interesting. I'll have to watch this one."
Were they looking at a budding Incident? They certainly didn't look interested in abiding by Spellcard Rules with how they handled poor Rumia. And he didn't seem like a pushover like most Outsider humans that wound up within Gensokyo. Surely some human that merely used firearms could be handled if he became problematic, right?

Only time and observations would tell and perhaps with the right intervention, they could be brought to heel. For now, he would be watched...