Inuyasha smirked as he looked at himself in the mirror, admiring his trimmed naked body and doing a couple of flex's even as he took in the three piece tux on the bed behind him in the mirror. It had been 5 months since he and Kagome had moved to the future (well her present) and he was loving it for many reasons. A lack of demon (well, ones who could put up a decent fight), no Koga and most importantly.. non stop accesses to Raman cups. 
Oh and being with Kagome and keeping her close to her family and all that crap.
Kagome was actually living at home still while taking some collage classes and though they had humored him and let him stay with them in the past, Inuyasha had been forced to go and rent a bedroom for him to stay in, at least until he made Kagome a 'honest woman.'
Thankfully her family DID put up the rent for the room and Inuyasha made money here and there doing odd jobs to pay for luxuries, not to mention he took to hunting his own food if he wasn't in the mood for ramen and for the most part it was working out great. 
'Still, can't believe it took 3 months to earn the cash for this stupid opera Kagome wants to go to.. Plus the rent on the monkey suit. Ah whatever.. she promised me all kinds of naughty naughty dirty sex fo-' Inuyasha was thinking with a smirk and then turned around, seeing Koga in his room holding a rolled up piece of parchment.
"How the FUCK d-" was as far as Inuyasha got out before Koga unrolled the paper and closed his eyes, turning away as a white flash filled the room.

Koga had been livid to find out that not only had the half breed gotten Kagome, they'd moved away out of his reach so he couldn't even attempt to get her for himself! the fact that he had his own wife and a pup on the way didn't seem to matter to Koga since it was less about charming and winning Kagome as it was about proving himself better once and for all to the stupid half breed. 
To that end Koga had gone out of his way to ransack and pillage money and valuables from local villages, marking his tribe as number one on all the demon hunters shit lists and then to the amazement of his tribe.. turned almost all of it over to a massively powerful and twisted old sage.
explaining who he was and what he wanted, the sage smirked, and agreed to help Koga but warned the wolf demon of a few thing. 
"One can't merely do as you say without giving up a few things. you'll be stranded in this distant future, doomed to never see your wife again nor your child." the old sage said, holding up one thin finger, a long dirty nail on the end. 
"You will also become corrupted and evil, and never be able to be truly happy unless you are making others suffer.. though judging from what you've done that won't be much of a difference." and a second finger joined the first.
"You'll be required to make the first part of the curse I'll give you for this half breed.. I could make it otherwise but well, I'm a dirty old man." And a third finger.
"And finally.. Should you try to reverse what you've down, out of a moments pity or regret..my curse will be transferred over to you. Those are the terms. do we have a deal?"
"What kind of curse are you go-" Koga had started to ask, but the old sage cut him off. 
"Deal, or no deal? It matter's not to me.. either way I'm keeping the riches you've brought me." 
"..Deal." 
And so, Koga was given a tattoo that would let him make use of the well, and with a scroll on hand to inflict the curse on Inuyasha and a bag containing part of what was needed for said curse, Koga had fled his life in the past with almost nary a second thought, even as the demon hunters the old sage had contracted came in for the rest of the tribe. 

Inuyasha wasn't sure how long he'd been out for as he sat up, head pounding and the room semi spinning as he opened his eyes, to see Koga dressed in the tux that he had rented and smirking down at him. 
"About time Sleepyhead. I was worried I wasn't gonna get a chance to see the curse in action." Koga snickered. 
"Ok I don't know what you think your do-" Inuyasha growled, scrambling to get to his feet and pausing as his balance was throw off by something and quick glance down had the dog demon blushing. 
He was wearing a fucking diaper!!
"Ok, Explain fast and I MIGHT give you a pain and painless death." Inuyasha snarled, claws out and ready to slice and dice. 
"Heh. Your not going to  touch me Inuyasha, much less hurt me. Not when I do this~" Koga said, and grabbed the satchel that he'd brought with him, opening it and making a face and blushing as he pulled out a filled to the brim diaper, and tossing it onto the floor just behind Inuyasha. 
"What the FUCK!? did you really come here just to diaper me so we could be poopie buddies or something?" Inuyasha asked, a hand going up to his nose, even as his ears twitched. 
god the smell was so strong and overwhelming! and it was so gross and.. awesome? without even thinking about it Inuyasha moved his hand away from his nose and sniffed deep, then again then took in more and more eager breaths. 
"You know, not gonna lie. I was almost half convinced the old sage was pulling my leg and just wanted to watch me shit myself. Buttt glad to see my little five minutes of shame is going to lead to a lifetime of poopie diaper worship for you." Koga snickered.
"W-What the fuck are you.." Inuyasha growled even as he felt himself growing hard in the cloth diapers pinned around his hips, tenting out the front and dropping to his hands and knees, crawling over to where the befouled diaper had landed. "W-Why can't I-" Inuyasha cried out, huffing in the stink, even as panic filled his voice.
"Why can't you stop yourself? Because like I said, Poopie diapers are your life now. I give it all of 8 hours, a day top before your discovered and kicked out and end up raiding dumpsters for your stinky diaper fix and more then likely ending up in a dumpster somewhere gooning your life away to till waste away. Meanwhile I'll be looking after Kagome who thanks to a love charm I got after doing a .." and Koga paused, blushing and making a face. "Extra favor for the sage who helped me out,  will forget all about you and be my blushing bride and we'll live happily ever after. or at least until I get bored of her. Either way, none of that is your concern right now." 
Coming over and raising a foot as Inuyasha was in front of the diaper, a hand down his own and jerking his cock hand though somehow keeping himself from planting his face in the bundled up thing, Koga broke his foot down and smooshed Inuyasha into the new love of his life and laughed as the pup squealed with delight. 
"Be thankful I have some SMALL mercies left in me. the poopie didn't have to be on the inside of the diaper. Oh, and don't think you'll be able to do anything but leak. you're never going to nut again." the watch that had been with the tux beeped and Koga looked at it, then gave Inuyasha a salute. "Anyways, looks like it's time for me to take off. Have fun with your new crush Inuyasha. I'd say you were a worthy foe in the game of love butttt why bother lying to a mutt?" 
And with that Koga walked out, closing the door behind him and tenting the pants of the tux as he heard Inuyasha start to sob even as loud smooching noises were heard too.

The end.