Not long, maybe a minute or two... I wouldn't even make it through one B-Komachi song, so I've got a ways to go before I can pull off your look.

[He poofs back quickly - while he can hold the transformation for a minute or so, it takes a considerable amount of focus. Even in his own form, Ango's hair is still a shade more purple than it was before, and there are a few stray ruffles left on his clothing that will take a few minutes to fade. It's an occupational hazard of being a writer (or ex-writer, anyway) - it's easy to lose a bit of himself in other people's stories. ]

Not exactly a lot of combat utility in that one, but I bet it's great at parties.