I was making Fortunate Son and Briar Side stories but I thought, what the heck and make side stories involving the Changling, though when it's him he isn't doing what he's doing from the kindness of his heart and more so what Hifumi sends him out to do in different worlds.
These Side Stories are Cannon mind you they just take place for the most part at a later time and place and when they do become officially cannon within the story I will reference the specific chapter they were in at the time.
Though I made this as a slight breather from the Demon Slayer stuff before he goes and takes the fight to both Akaza and Doma.
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Suddenly in a flash of light a young Japanese man falls from the sky before landing face first on the cold hard ground and laying there before getting his bearings straight.
This young and unfortunate boy is Touka, Mimori Touka, and he was unfortunately discarded by the goddess who summoned him to this world thinking he was useless as all his skills were only E-Rank, the lowest rank of skills in this world, and was discarded to this ruins better known as, funnily enough, The Disposal Ruins, where all the trash summons the goddess has ever summoned are sent to die as they are 'of no use to this world.'
"Mmmggghhh…." The boy groaned out as he slowly began to pick himself up from the ground as he looked at himself before dusting off his clothes while he looked around at this dimly lit cave.
"Where…." He was about to ask where he was but the words got stuck in his throat as his eyes widened a bit to see what appeared to be a house built down here deep under ground.
Not only that it appeared to be a modern Japanese looking house, a fancy one at that, seeing this deeply confused the boy, "Why the hell would there be a house down here, this is supposed to be some ruins right then why would-" But as he kept talking the front door opened before suddenly a force that he couldn't fight against brought him inside the house before locking the door behind him.
"Don't be alarmed, I just didn't want to keep waiting for you to eventually come inside this house." He heard an ethereal voice speak to him, and while he was a bit freaked out, he hadn't been attack as of yet and with his rather dark and violent childhood from his abusive parents, he could tell whoever this is was both strong and powerful, someone who could kill him but wasn't going to.
Soon enough the door in front of him opened and seeing no way out of this he took off his shoes at the door and entered where he appeared to be within a traditional Tatami styled room as an older man wearing a rather peculiar suit that seemed familiar to him, not only that but the old man seemed familiar to him, like he had seen the man but never met him in person before.
The old man was calmly drinking tea as Touka came in before taking a seat before the old man as he looked at the cup of green tea that sat before him.
"Don't worry, it's not poisonous, besides it should be very clear to you that I don't need those types of petty tricks to deal with a kid like you." He says getting straight to the point which Touka agrees internally as well to which he took the green tea and drank from it.
"Scary isn't it? Being summoned from another world, far flung from anyone you cared about, suddenly being deemed as worthless trash by an equally worthless goddess and sent here to these ruins to die, your fate is a rather pitiful one, but I must call her useless as she misidentified your skills as useless but in all actually are so over powered that even the simplest of spells and skills in you hands breaks the very frame of power levels for this world, it was even given a name at that, The Failure Frame, not that you are a failure in the frame of power of this world but the frame of power in this world is a failure to you." The old man said to him before revealing Touka's real powers as not E-Rank but EX-Rank as they have gone well and beyond.
He sees his own innate skill of Abnormal State Endowment along with all the different status effects he can use on his target and that no matter the power difference between him and his target his ability to give abnormal status effects to his enemies is always 100% chance.
He could use Paralyze, Poison, Sleep, Dark(Blindness), Berserk, Freeze and Slow, normal situations all these skills wouldn't matter to the truest powerful of beings but with his broken skill that goes beyond the boundaries of mortals and could even injure the gods themselves.
"Now don't let this sudden information of power go to your head, I didn't give you the information of your powers or what you can do with them when you have enough energy to use them free of charge, everything has a cost, and everything has a price." The old man said making Touka gulp and nod, "I understand, what do you need of me?"
Hearing this the old man nods, "It's simple really, it's something both you and I want to happen, The Useless Goddess who sent you here, the one who deemed you a failure, and the one who is going out of her way to make the world worse of her own accord by wishing for its entire annihilation due to her own personal boredom with all the mortal races of this world, I want you, Mimori Touka, To Kill Her and to give the her God Soul to me, in exchange for that I shall give you necessary levels to survive down here, the weapons and skills to make it out of here alive, think of it as a test from me to you to see if you are worth of this task, to let you get back at her for what she has done, and yes I of course could get you out of here and to the surface with a mere snap of my fingers but you need the experience of fighting for your life and the drive to actually kill monsters and mortal beings with your own hands before you have hardened your body and mind to personally hunt down and kill the Goddess Viysis yourself." The old man went onto explain to Touka.
Now Touka was afraid as he didn't know what he would face in this hell hole he was sent to, but with everything that happened to him in his childhood a purple flame began to ignite within his eyes as he looked up at the old man, "I accept, but I hope you can answer one question of mine in return."
The old man grinned, "Ask away."
"Why do you need the Goddesses soul?" Is the one thing on his mind, was it for power? To become a god himself or even-
"Her soul would be a great trump card in my masters arsenal to protect the ones he loves, and to protect his world from the threats that wish to seek its destruction." The old man said honestly and truthfully as Touka felt no lies or tricks in what he said.
Saying that the man held out his hand, "Then, do we have a deal?" He asked to which Touka nodded before taking this mysterious old man's hand as the deal was struck.
And with that deal this world was going to change sooner than anyone could ever anticipate.