Sneaky Momiji is sneaky sneaky.

GJ Momiji!

I can only guess what Reimu and Momiji are thinking with this embarrassing picture of Aya and Hatate:

1.) Momiji's revenge for being Aya's "guinea pig" (as well as being left out now that Aya/Hatate is on the rise).
2.) Reimu can now - finally - blackmail Aya (and perhaps Hatate) with this into making more... *ehem* credible news.
3.) ???
4.) PROFIT!

So if Aya's the fastest in Gensokyo, how the heck did momi get back to Reimu before she did?

Aya had to change before starting out. Flying at Mach 5 with only a towel on would be quite risky in one particular way.

Or probably Reimu lent Momiji some gaps (courtesy of her onee-sama Yukari)?

Momiji passed at the top of her class