The Gate

The Gate is a sentient being and is literally the gate that the goddesses (among other beings) use for travelling between worlds - on Earth, she looks like a young girl. From people who travel through her, she gathers information that even surpasses the knowledge of the goddesses. But when Peorth is recalled to heaven concerning an urgent matter, she can't return because the Gate went on strike. Summoned by the goddesses, the Gate appears at the temple and wants to have first hand experience on real life, emotions, and specifically, romantic relationships (we later find out that's why she came to Keiichi and Belldandy - their story has made its way even to her.) She sometimes feels alone on her ancient duty of letting people travel through her and wants to overcome that by experiencing love from Keiichi - unaware of the complexities of relationships and honest love. After some more incidents (and one of Belldandy's jealousy storms) the Gate begins to understand what Keiichi and Belldandy's relationship is all about - and that loving someone is not as easy as she thought - and returns to her duty. (from http://ohmygoddess.wikia.com/wiki/Gate)