Sophia

You wake up on a Saturday morning. You go outside to get some fresh air, but there's something off. Someone put a giant egg on your front lawn! You go over to inspect the egg. It's white, with several cyan-colored spots on it. And there's a note attached to it. It reads:

"You don't know us, but we hear you've been feeling down recently. So take this special Yoshi egg. We're certain that she'll help get your spirits up. But be careful, once you touch this egg, she'll be free. Remember how we said this egg is special? This Yoshi isn't like a normal Yoshi. She's quite a big one, a bit of a klutz, but we're sure you'll get along just fine. Her name is Sophia."

Next to the egg, are a few large boxes of large yellow mushrooms with red spots. There are also similar mushrooms inside, but with different colors. There's a note on this, too. It says:

"Feed her one of the yellow ones if you want to make her fatter. Be wary, just one will make her grow ALOT. You should hide them so she doesn't eat them all at once. There's also some other colors of 'shrooms in here, but we'll let you find out what they do on your own."

Surely enough, you touch the egg, and in a poof of smoke, in it's place sits Sophia, still asleep by the looks of it. You understand that the note said she was big, but she's about twice to three times the size of you. And that's not just the only thing that's big about her. She's quite fat as well, with wide hips, a short, thick tail, fat chunky thighs, a chunky belly, and an ass fat and big enough to sleep on.

You can see her start to wake up. She yawns big, then looks down at you with a big smile. She picks you up and nuzzles you.

Haiiii! You must be the one they told me about! I'm Sophia. And...uh...I'm sure we'll be fast friends!