Around year 2030, a small business, called Change O' Life was started. What did they do? Well... they could transform a person into almost anything, in a wide array of forms. They could transform them into animals, mythological creatures, inanimate objects, machines, someone's body part, or replace or modify their body. It started as a small bussiness, but in less than two year it became the biggest company in the world. It changed everything: cosmetic surgery became obsolete (but smost surgeons ended up working at the company, since their knowledge was extremely useful), transgender people could have the body of their dreams, criminals were rehabilitated by applying mental changes to them (and the punishment for some crimes was an undesired transformation), it made the death rates plummet and quality of life rise enormously, entire groups of new races founded their own countries, war was completely abolished...
Eventually, the company changed their name to "Morphers", and their transformation centers were called... well, "TF Centers". This came with a change in methods too, which allowed to transform people into virtually anything. Hell, some people were even transformed into planets, and left in space to live their inmortal lives as giants... but, of course, they decided to put some restrictions to prevent undesired events. By year 2061, their methods achieved absolute perfection.
And here you are. At your city's TF Center, the first one ever created. Truly, a living legend. And they're going to transform you, so you can start a new life... Your current self is Kate Ylviosa, a normal 21 year old lesbian girl, but that's not going to last for soon. Everyone you know is supportive about this.
As you cross the door, everything is just like you imagined. A giant center which has a slight resemblance to an airport, full of people entering and exiting, and tons, tons of items being carried away. You see everything: impossible women, handsome centaur stallions, cute catgirls, sexy nagas, marvelous statues, pretty mermaids, disembodied body parts... all of this is so awesome... You then look at a nearby machine, which says to type your name on it if you want a transformation, so they can put you in the queue.
You obey as told, and type your name and surname, wondering in your mind what you're going to become...