escav said: I'm getting Morino Hon vibes from that Hourai.
I actually went back and reread the whole series, and noticed that all the characters in that video are also the ones that appeared in Omoito, save for Reimu. There is even a scene with Hourai being annoyed by Marisa, and a scene with Alice having (much more casual) tea with Yuuka.
It's quite random, but I'd say it's safe to say that it's based loosely off of Omoito.