An idea I got when I saw a picture of the Vocaloid Miku dressed like Sonic.
Credit goes to the creators of their respective series and/or fan characters.
TouhouShake owns Cassie, Lily, Mimi, and Yama.
Just a normal day for the vocaloids. If you could consider it normal. Luka was stuck babysitting both Miku and Rin which wasn't fun. To add to it Rin had practically bribed her to take them to a video game convention. Luka was okay with that. She wasn't okay with the fact that it was required to wear a costume to the convention. She was currently dressed as Amy Rose. Obsessed fan girl and stalker of Sonic the hedgehog. Rin was dressed as Tails and looked rather cute for a first time cosplayer. And Miku… Luka had a feeling Miku was the ones that made their costumes. She was dressed as Sonic the hedgehog. Luka swore that she would get revenge.
The convention itself wasn't that bad. Miku was busy looking through the Sonic games available while Rin was looking for Combat 21st century. Luka just went and looked at the new Starcraft game, Starcraft Ghost. She was happy she was able to get a copy. When they left they all had gotten the game they wanted. Then Miku did what Luka never expected.
"Hey Luka?" Miku asked as she looked at the older vocaloid.
"What's up?" Luka asks as she forgets all about the hatred she had for Miku.
"I'm happy you liked this." Miku said as she skipped ahead.
"I'm surprised she forgot about the fight you put up when she tried to get you into the costume." Rin says as she catches up while caring a bag containing a copy of Combat 21st century along with a model of almost every vehicle in said game.
"MIKU!" Luka yelled as she remembered why she was so mad at her.
"If it's about the costume the reason I gave you it was because it matched your hair." Miku says as she turns around and walks backward.
Before Miku, Luka, or Rin can say anything else what looks to be an interdimensional portal opens under all three of them.
Meanwhile five Hedgehogs are standing in a room doing various things. A male hedgehog with light blue fur and black quill highlights is looking over a machine that is making a portal. A female hedgehog with almost the same color of fur is looking around the room and looks at the three other hedgehogs that are basically arguing. She then spies to small creatures sleeping in the corner. The other three hedgehogs are all female and are brown, green, and black respectively.
"Will you three please quite down a bit. I mean we wouldn't want to wake Yama up. She bad enough when she wakes up in a bad mode already but if he wants to. I have a point right, Cassie." The male hedgehog says as he turns to the black furred girl that is arguing.
"Your right Nate. But things like this happen on occasions. I mean after all having three girls sharing the same body does things to their sanity. And please refer to Mimi and Lily by their proper titles." Cassie says as she looks at her friends Lilith and Miranda. She was more referring to the fact that while in formal events he still called them by their nicknames.
Just then two hedgehogs and a fox end up tumbling out of the portal. Nate laughs as he looks at his sister Miki who is somewhat shocked. He then looks at his three friends. Mimi is pretty well interested while Cassie looks shocked. Lily is slowly drawing her gun in case anything bad happens. His attention is then turned back to the three new arrivals. A hedgehog with pink quills that touch her ankles slowly gets up and stares at the five hedgehogs in front of her. The next one to get up is the other hedgehog. She ends up getting caught in her quills which happen to be styled to be two extremely long cyan ponytails. She then ends up crashing to the floor in a loud bang. This makes the fox scramble onto her feet.
"Miku! What are you doing." The fox, presumably Rin, asks as the hedgehog gets up.
"Since when did my hair go this far down." Miku asks as she manages to not trip over her ponytails.
"Better question. Who are you and what are we doing here?" Luka asks as she stares at the hedgehogs in front of her.
"I'm Nathan but everyone calls me Nate. The girl that looks just like me is Miki. (Face palm.) The brown wolf hedgehog hybrid is Lilith but everyone calls her Lily. (Raises hand to argue but then looks down admitting defeat.) The green hedgehog is Miranda. (Waves.) And the hedgehog is Cassandra but everyone calls her Cassie. (Looks at Nate and then does the same thing Miki did.) "Nate says as he explains.
Just then everyone hears to simultaneous yawns.
"Um? Hi? Is this a bad time?" Faith says as she sits up the best she can.
"Ugh… What did I use for a pillow?" Yama says as she sits up and rolls her head which results in one of her neck joints letting out a crack. She then turns and stares at Faith. She then notices her position relevant of Faiths. "Oh. That's what I used."
"And those two are Faith and Yama. Yama's the cat and Faiths the plushie. Also as to why you're here. You three seem to have been somehow sucked into the portal we were testing. Can I get your names? I already know that the hedgehog with ponytails is named Miku so the other two introductions are in order." Nate says as Faith and Yama both lung for Miki which results in her being knocked over. When she stands up she is holding Faith by her quills and Yama by the neck.
"I'm Luka and that's Rin. But what did you mean by calling Miku a hedgehog. Last time I checked we were humans." Luka says as she stares at the other hedgehogs and kitten.
"One you and Miku are hedgehogs and Rin is a fox. Two if I might add don't you mean you three were humanoid robots called Vocaloids." Mimi says as she goes and takes Yama from Miki.
With that statement all three girls look at themselves. Same clothes. Same hair. Different species. The only difference besides the species change is the fact that all three have a much larger version of their regular outfit on and their hair is much longer.
"Okay three more questions. How did you know about us Vocaloids? How are we a different species? And what did you mean by that hedgehog being a plushy?" Rin asks as she gets over the shock of being a fox.
"First off Mimi herself is a Vocaloid so that's how we knew of Vocaloids. Two I have no idea how you three are stuck as hedgehogs and a fox. Finally it's kind of complicated but Faith is an energy being that possesses a plushy to use as her body." Nate says as he looks at them. "Anyway welcome to the world of Mobius. If you want I'll let you three stay here. We have enough spare room."
"Wait! Mobius as in the world Sonic the Hedgehog lives on." Luka asks as she stares at them.
As if on cue Shadow walks into the room and looks at everyone.
"Humph something going on here?" Shadow asks as he looks at the three girls that have dropped jaws. He then notices the spinning maroon buzz saw that is Faith while in full motion. "Oh crap!"
Shadow is promptly tackled by the maroon hedgehog. As he is getting up with Faith on his head hugging one of his quills to death Nate turns back to the three newcomers.
"I'll take it that answers your question." Nate says as he goes to find a crowbar to get Faith off Shadow.
"Miku this is your fault we are a different species." Rin and Luka yell at Miku simultaneously.
"My fault?" Miku asks as she stare at the two other girls.
"You're the one that made us wear costumes to the convention. We were wearing those exact costumes when we got sucked in the portal. And last those costumes were the same species we got changed into." Luka says as she picks up the bag that contained her and Miku's purchases. Rin does the same thing with her bag.
"Why are you being mean sis?" Miku asks as she looks at Luka.
"Because I'm mad and I don't have anything else to do to you." Luka answers.
There done with chapter one. And yes I do know Miku and Luka are not siblings. To me they seem to have the same relationship Amy and Cream have. They see each other as sisters and treat each other like sisters.