Hello fellow Ben 10 and Monmusu fans. Seeing as there are very few stories in this crossover category I've decided to fill the void with this. Similar to my Shota Ben fairy tail story, this Ben will be a young one with several girls who are a bit older.

Not just older though, they're also hot and sexy monster girls.

Now before any of you tell me to piss off, rude by the way, I already fixed the issue. My age limit is now and forever 13, so don't go getting on my case about the age difference, or else you'll find yourselves at the merciless hands of a Succubus or incubus. And guess what boys, demon lady's on top and got a "Toy" to use on you. So keep your clap traps shut. Anyways here's chapter one, for disclosure Miia will not be in Ben's Harem.

She'll be Kimihito's one and only, others however are fair game, anyway here's our first girl, everyone favorite adorable cute bird brain.

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On the balcony of the Kurusu residence, a familiar brown haired green eyed boy was seen helping a tall snake like girl hang up laundry. This as anyone could even guess is Ben Tennyson, holder of the most powerful weapon in the universe and the cutest little super hero anyone will find. As to why he's in this place instead of in the rust bucket annoying the snot out of his cousin Gwen, it's actually a long story.

You see after a trip to Massachusetts and a disagreement between him and his grandfather concerning his powers when he attempted to hack the other Omnitrix, their enemy Hex attempted to use the magic of long dead witches to remake the modern world. Only to be severely disappointed when most of the energy from said witches had turned out to belong to innocent people who were accused during the trials back then. In his anger he decided to use his powers to wipe the Tennyson's off the face of the earth.

At the time Ben's Omnitrix wasn't charged so Max told Gwen to handle it and for Him to just stay out of it. For both of them to get knocked out by a floating lamp of all things. While he was agitated with Gwen's taunting that she could handle this situation better than him and grandpa Max's repeated lectures about not over using his abilities. Ben didn't want to stand by and watch one of their worst enemies destroy them, he constantly tried to activate his watch but it wouldn't turn on, so when Hex was about to blast Max and Gwen. He jumped in front and took the blast instead which had, as Hex stated, wiped him off the face of the earth.

The two were horrified that Ben was gone, Gwen regretting every bad thing she's ever said to her cousin, and Max feeling bad himself since his grandson sacrificed his life to save them after he lectured him non stop. Thankfully Hex was too weak from his blast that he, turned to dust... (I'm no expert in magic so someone got an explanation? Immortality magic maybe?)

What they hadn't known was that Ben was actually fine and unharmed, the spell that the dark wizard used had wiped him off the face of the earth. Though not in the way you'd expect, Ben wasn't destroyed, he was transported to another earth. Though I may not be magic I know a few things about loopholes, and I dropped him off in a very interesting world. One with over the top extremely hot busty monster girls (drooling) when Ben came to he found himself in an office chair with a rather attractive woman with black hair wearing an office suit sitting on the chair across from him.

(A/N: anyone here think office suits are sexy as hell? Because I sure do and Smith is making it work!)

She was apparently an agent of of an organization of the government meant to handle anything Interspecies related. Basically her jobs deals with other species, not aliens or animals but different races of people, not like African American or anything like that. Think beings such as Centaurs, ogres or mermaids, in this world they're as real as you can get and have been steadily introduced into normal society. The woman, agent Kuroko Smith, had found Ben when driving around on patrol after a big light flashed.

After explaining himself Smith decided to put the boy under the interspecies exchange act for multiple reasons, mainly because being he was technically an extra species. Ben may have been a human, but he was still a human from another world so that met a requirement. Additionally the boy told her about the Omnitrix which had cemented him as an extra species labeled "super powered human".

This had given Ben a lot of loopholes in the exchange surprisingly rather than restrictions, a few important rules of the exchange were that humans weren't allowed to attack extra species and vice versa, Extra species exchanges were not permitted to go out by themselves and humans and extra species were not allowed to bang each other. (A/N: personally I mind since I'm... well you know, but also don't mind because that means I don't have to get near the male centaurs or orcs, yuck!) since Ben was both human and not human he had many freedoms. One thing is that he was able to attack and defend himself from both parties, like say if someone was being robbed or if he was attacked by either side he was allowed to attack to stop them or in retaliation.

That also meant he could go out if he wanted, and that he was allowed to bang any monster girl or human girl he saw fit, though he thought that to be illegal to tell him. Until Kuroko also told him that the age of consent in Japan is 13 (A/N: true fact, I searched it up and scary part is the youngest is 11 in Nigeria, glad I was raised where I am).

Smith Had placed him under the care of a person by the name of Kimihito Kurusu who was also watching over a Lamia (snake girl) named Miia. So far he had adjusted well, Miia certainly took to him quickly saying he was downright adorable and had asserted herself as his big sister, while Kinihito hadn't minded Ben around and enjoyed having another guy in the house to talk to. And in doing so also lead him to calling Ben his little brother, he really did appreciate Ben's powers with XLR8 helping the man with some work around the house. Especially with cooking since extra species like Miia tended to eat a lot, turns out the Ben was actually pretty good with food, good thing because he definitely wouldn't want to constantly eat Max's horror level food anymore.

The day was going well so far, the day before Kimihito took him and Miia out around the city to explore the area, as it's a requirement for the interspecies exchange. And after a hiccup involving an insensitive racist couple and their host punching their lights out Miia was even more infatuated with him. "I'll help you with those Miia" Ben said turning into Wild Vine and stretched his arm across the clothes line hanging up whatever clothes they had.

When Miia went to praise her "darling" Ben chuckled as he changed back and continued with the laundry. 'While I miss Grandpa and Gwen, this isn't so bad' he thought hanging up more laundry, then out of nowhere he felt a fair amount of weight hit him "Gah?!" The impact knocked Ben forwards and he felt his head collide with the railing on the house.

The last thing he could hear before fading into unconsciousness was Kimihito and Miia exclaim in panic.

When Ben woke up her saw that he was in a park with several people going about their day "when did I get to the park?" He asked rubbing his head where it hit the railing. "And why does everyone look so short?" Looking down Ben got his answer, some how the little guy was stuck in a tree!

"What the heck?! How did I get up here?!" He exclaimed tightening his grip on the branch, "oh you're awake!" A young female voice said. When Ben looked to the source he saw a girl, she had short blue hair, a slim and petite body, she had bird like legs and her feet had talons and her arms were wings covered in blue feathers.

"Huh?" "Papi is a harpy. That's what Papi is" she said, "what? Wait what am I doing here? Why did you kidnap me... also mind getting me down?" Ben asked.

She obliged and gripped him in her feet before hovering down, "Thanks, seriously though why did you snatch me?" He asked her again "you know that rule where you're not supposed to go out alone? Well that's why I brought you" Papi explained "well I'm not your host. Heck I'm too young to be one, heck again I'm actually a Linimal myself" Ben replied, only for her to wander around three steps before looking to him "huh? Who are you?" 'Oh god this girl's an air head... sure is cute though' he thought.

"Oh there! there!" Papi yelled dragging him over to a good cart "hey watch it!" He shouted, he then bought her an ice cream cone while he got one for himself. "It was fortunate that I had my wallet with me when you snatched me" Ben grumbled as the harpy had bobbed her head and kicked her feet, eager for her frozen treat... ( Flamewarrior11 Humatrix-X-24 look I made word play!... LET IT GO! LET IT GO! (Constantly dodging the tomatoes from people who get annoyed by the let it go song) CAN'T HOLD IT BACK ANYMORE!)

"Wait, so how are you out all by yourself?" He asked, "oh I snuck off when the terminator turned around" she replied, not noticing her cold snack was about to fall. "Watch it" Ben said readjusting it so that it wouldn't fall "oh thanks" Papi replied licking her ice cream "as for the so called Terminator, I think you mean coordinator. As in the interspecies exchange coordinator, you probably shouldn't have ran off" He said.

"Papi does it all the time, but they said the next time I do it they were gonna deflower me..." she added making Ben cough and accidentally smash his ice cream into his face "(cough!) (cough!) Deport! I think you mean Deport!" He exclaimed. This startled Papi but she did notice her new pal's messy face "oh man, wish I asked for some extra napkins" he groaned feeling the ice cream on his cheeks and around his mouth. "Oh Papi can clean that off for you!" The bird girl said "no thanks, I can handle it myself... EEP?!" Ben was saying before she cut him off by licking his cheek, "p-p-Papi?!" He said trying to push her off. But she continued to lick his face to clean it off, "I'm not kidding knock it off, Papi stop!" Ben said as she continued her little assault.

After an entire minute she was finally done, with Ben looking very flustered from essentially making out with his new harpy friend. Especially since a few times she managed to unintentionally get her tongue into his mouth when Ben protested.

"I basically had my first kiss taken away" Ben said trying to drown his embarrassment in the last of his ice cream, "hey" he heard Papi say, looking to her she was looking back, then had pulled something off his face. Which had been revealed to be her feathers "I guess we're pretty sticky" she giggled "great go take a bath later, I'm gonna try to contact my host... WHAT ARE YOU DOING?!" He shrieks seeing the girl strip down before jumping into the fountain "that isn't a bird bath get out of there!" Ben yelled trying to reach for her "oh wait" the boy then turned into Snare-Oh! And grappled Papi "got yah... AHH?!" Only to get pulled by the surprisingly strong bird "come on you join to!" She cheered.

"LOOK THERE HE IS!" He heard his snake like big sis say, "Miia! Kimi! Over here!" He exclaimed only to have the top portion of his body being dunked, "AHH I'M SOAKED!" He said trying to pull himself out.

Skipping over some stuff and to keep it short, Ben manages to save a girl from a tree with Wildvine and with Papi's help, Smith arrives to get the harpy and Papi joins their little house. "Congratulations Papi, you'll be staying here, from now on" Smith said shocking Kimihito with how irresponsible she was.

"Yay!" Papi cheered, "be sure to listen to both Darling and Ben here, he's the master of the house and Benny's the one who's in charge when neither darling or Miia are home" Smith added "got it Master!" Papi saluted time the older male.

"Oh boy, I'm gonna go take a bath, I smell like a park fountain" Ben said walking to the bathroom 'and harpy tongue, not that I'm saying that out loud' "oh me too! Take a bath with me Ben Ben!" The bird girl cheered hugging him from behind. "H-Huh?! But that's illegal!" He squeaked, "not for you two, remember Benny you're both a linimal and not, not to mention I told you that the age of consent was 13 here in Japan" Kuroko added making him pale more. At first Miia protested but she was somehow convinced otherwise. In the end Ben wound up in the bathroom with his new housemate, 'geez this is embarrassing' Ben thought taking off his clothes and walked in. And had a minor nose bleed seeing Papi swim around in the bath naked as a bird actually is. "Ahh this feels great" she said floating in the water.

"D-Don't move around so much... the water's gonna splash out" he said getting into the bath, Papi nodded and sat up before looking at him. "Hey what's..." she spoke scrutinizing his body, specifically the lower half of it, which didn't go unnoticed "H-Hey! Where do you think you're looking?!" He said turning his body around "oh you have one of those... thingies!" She said making Ben embarrassed. "Yeah so what?" "Just saying because I've never seen one, or at least I don't think so, us harpies are all female" Papi said.

(Lemon warning!)

"Well please keep you talons to yourself" Ben pleaded, only to be wrapped around by his new friend's large wings "hey! What did I ask?!" "You said to keep my talons to myself! Not my wings! Tickle fight!" The girl then proceeded to tickle the shapeshifter making him go into a laughing fit. "S-stop!" He laughed trying to swim away, he managed to escape the bathtub only to be hugged again by Papi who jumped out of the bath, which forced Ben to turn the tables and put Papi into an armlock "Hah! Now looks at who's trapped" he gloated. Looking directly at her face, he wasn't paying attention and had actually locked his arm's around her in the same fashion as a hug, meaning that right now he was not only face to face with Papi, but also chest to chest and groin to groin.

He blushed at this "s-Sorry... I'll le... Hmm?!" He was taken by surprise when Papi suddenly kissed him, 'what the heck?!' He thought trying to wrench his face away from her's. She didn't let up however and threw her legs around him, then had pulled away panting "you're so cute" she spoke making Ben blush before resuming to kiss him. Then began rubbing her body on his, 'dang it why is she doing this?! More importantly why am I starting to do the same?!' True to the thought Ben's body was moving on its own. Then out of no where his little friend, who became hard from the tickle fight earlier, had unintentionally pierced its way into Papi's sacred hole.

"Ah?!" They gasped, "it... it's really big" the bird wheezed. "Y-you're so... tight" Ben moaned, the two had stayed in the bathroom sitting on the floor with the bird like girl bouncing on Ben's lap facing him while he thrusted in and out of her as if his body was on autopilot. "B-Ben Ben... I feel so good" Papi moaned, "d-don't day that... you're gonna make me go harder!" He growled, "Ben Ben! I'm close!" She squealed "I gotta pull out! I got a pull out!" The boy said but unfortunately Papi's body being extremely limp right now on top of him made it impossible.

And impossible it was because right when he managed to pull out of the harpy she let out a small shriek into his mouth when she suddenly kissed him and released herself on his rod which had shot its load on her currently dripping hole.

Lemon over

The next day we see Papi cuddling Ben in bed, "Papi... what are you doing?" He asked getting really uncomfortable in a certain place. "Hmm... Papi wants to stay with boyfriend Ben Ben..." she answered pecking his cheek making the emerald eyed youth blush. "Oh jeez... I hope this doesn't start becoming a regular thing with her" Ben said, then noticed Miia slithering into his room looking for something to cuddle with in order to warm up "Kimihito must've left early to... wait Miia don't!.. GAH?!" Too late though as she had already grabbed onto the two and cuddled them for heat.

'Unfortunately I already know this will be a regular thing' he thought as Miia' grip began getting a bit tighter.

Hope ya'll enjoyed that chapter,stay tuned for part two when a certain slime girl makes an appearance. Yes I already know it's out of order but I goofed and it's too late to change it.