This is a short, 18-pages long doujinshi comic drawn by the character designer of original series, Ume Aoki.
There`s no 'story,' actually. The whole comic consists of few 4komas(that were supposed to be included in BD/DVD booklets, but were left out in the end) and illustrations. The 'art' category is where it shines the most. There are a lot of colorful pages as well (most include Homura). Me Aoki wrote some of her thoughts about the characters too, and there is a picture of each one in casual clothes(which are nice to see, since everyone except for Kyoko always wears uniforms). There is also a short
KyouSaya comic in the end, which is sure to make the pairing`s supporters happy ( XD)
If you're a fan of PMMM, then spend a few minutes on reading this and enjoy yourself~