Well I figured it'd be a good idea to post this spell here as opposed to somewhere like SpellsofMagic because I repeatedly got bashed saying magic couldn't cause physical change. But just a quick disclaimer. Magic truly cannot do everything. That doesn't mean being a neko or avian isn't possible. You just need to shift mentally and use spells and keep that balanced. Now, onto the magical girl spell, for all you weaboos out there.

1.  Sit silently and meditate on the deity of your choice.  Once you feel you have successfully called upon it, begin the spell.

2.  Make a circle out of the pictures you have.  Both the pictures of your powers, and the pictures of your form/s should be used. 

3.  Sit down in your circle.  State your EXACT wish.  Right down to every detail.  As you do, visualize you as your form, using your powers.  Like its already happened.  Try to do this as vividly as possible.

4.  After that, lay down on your back (stay in the circle).  Bring your heels close to your lower back.  Put your legs together when doing this.  Once your heels are almost touching your lower back, begin to spread your knees apart, while keeping your heels together.  Spread your knees until they begin to get painful.  Once at that point, hold them there for at least two minutes.

5.  During these two minutes, close your eyes and visualize your deity.  Direct your next few words to that deity.  Speak something along the lines of,

"Dear (deity), I offer myself to you.  I seek only your help in the completion of this task.  In this moment of my vulnerability, I humbly ask that you grant my wish.  In return, I give you (your offering).  This is very precious to me.  As precious as my wish.  Please take it, and grant my wish in return.  Blessed be, in any decision you make."

6.  Sit there for as much longer as you can.  Keep visualizing your wish like it's true.  

7.  Get up, and gather all of your pictures, and your offering (if it's physical.  If it's not physical, then just remember what it is).

8.  Go to somewhere outside, that you feel is appropriate, and place your offering there.  If it's physical, bury it.  If it's not physical, then attach it to an item like a rock or stone or tree, and give the deity permission to take the offering.  Hold all of the pictures to your heart and whisper the wish once again, to yourself.  Then walk away, and as you do so, feel like you are walking through a doorway, into a new life where your wish it true.

Keep the pictures handy, or just throw them away.  Just make sure you remember your form and powers.  There ya go!  Your Magical Girl spell!

Of course the side effects can be pretty drastic. They include energy loss, feeling weak, difficulty doing physical activities and generally feeling like shit.