@haegar
Well as far as we know Tsukune doesn't know Jigen-Tou, it's possible that Touhou taught him during the month of training since it wasn't shown, but it will probably appear in the future as a flashback of what happened during his training, if it did happen that is.
As for Akua, let's not go with the harem thing for now, but she will indeed go through great change after her encounter with Tsukune.
Jigen-Tou is one of the most advanced Youjutsu techniques, but now that Tsukune has a reconstructed body that can use Youjutsu, than him learning Jigen-Tou can happen.