Project A-Ko 2: Plot of the Daitokuji Financial Group

It's summer in Graviton City, and the girls all have a break from school! A-Ko decides to lose a few inches, C-Ko makes a list of all the cool things that she'll buy, and B-Ko vows to get A-Ko out of the way once and for all so that
Three weeks have gone by since the alien spaceship crash landed on the Graviton City spire, and since then the aliens have been hard at work converting their ship to a pleasure district, hoping to make friends with the humans!… Not. Perpetually late and continually over-eating A-ko, spacy and cheerful C-ko, and brilliant and bold B-ko are about to enter summer break from school, and it just so happens the alien ship is open for business. When a free meal turns into a sob story about how the aliens just want to go home, will it be A-ko or B-ko who can get the ship into orbit again?