Episode 26:
Aa! Doki Doki ha Otona no Aji?
Ah! Being an Adult is Heart-Throbbing?
Manga Chapters: 041, 051
External Links:
Gateway to the Goddesses [041]
Gateway to the Goddesses [051]
Wikipedia
Token Asian's Anime Blog

This episode is mostly original material. The situation is that Skuld progresses in age rapidly because her emblem synchronization has gone out of control, she has a day to be an adult before Yggdrasil causes her to go back to normal. Originally in the manga it took several months before Yggdrasil was finally back up and running. I suppose since this is in "modern" times they have better tech support or something.

Holy crap, Aya Hisakawa sounds awesome as an adult! Heck, even Annice Moriarty sounds not-annoying as an adult!

Like I said, this episode is mostly original material. Even when Skuld goes out on a date with Keiichi in the manga, she's still a child, so none of the events are the same.

Still, despite my obvious dislike for Skuld, I really did like this episode. It brings out a lot of Skuld's character. Um... yeah. Not much else to say.