The story unfolds with a view of a girl descending from a mystical place. Garbed in a flowing blue-and white dress, she utters a chant while forming ball of blue light in her hands. The light expands and engulfs the scenery…

The scene zooms to Morisato Keiichi, a college student left by his friends to watch the dorm and take messages for them. While house sitting he feels hunger pangs but is left with only an empty potato chips bag. Deciding to order take-out, Keiichi dials several times but doesn't succeed because all the places were either not accepting take-outs in this hour or were not answering the phone. Frustrated, Keiichi dials a number and reaches the "Goddess Relief Office." A certain "Belldandy" receives the call and says she'll visit for a consultation. Suddenly the mirror behind Keiichi begins to ripple and swirl. Keichii turns to the sound of a female voice and comes face-to-face with a girl half sticking out of the mirror. Keiichi scoots away in fright but the girl, introducing herself as Belldandy, reassures him that she is goddess who helps people in distress. She tells Keiichi that he can grant him a single wish and with this several fantasies of girls, money and, fame flash through his mind.However, Keiichi decides that his friends are trying to play a joke on him because they know he can't get a girlfriend. With this on his mind Keiichi asks an unusual wish….for "a goddess like you to be with me always." The marking on Belldandy's forehead blazes and a beam of light shoots to the heavens. With a smile Belldandy says his wish has been approved and that they will be together thereafter. Keiichi is shocked, and argues that his dorm is for men only. Belldandy assures him that all will be fine because when a contract is made the so-called the "Ultimate Force" starts to work. This force makes sure that the contract will be fulfilled, and is so strong that even a goddess cannot resist it. Just as Belldandy mentions that she could feel it starting to work, Keiichi's friends come back. Having broken the dorm rule against women inside Keiichi gets thrown out.

It's evening as the couple drive off in Keiichi's motorcycle to look for a place to stay. With no luck in finding one they decide take a break at a park where Keiichi buys some hot drinks. Keiichi asks Belldandy why she came to him of all people, since there must be a lot of other people who wanted their wishes to come true. The Goddess explains that that certain qualifications are required in order to get a wish and that Keiichi fulfilled those. Keiichi wonders if a contract that was made can be broken but Belldandy does not know. However as long that he needed her, all will be fine. Belldandy mentions that they should go to the west where Keiichi will  find  what he seeks.  On the road  they encounter  a sports car on a head-on collision. Belldandy uses her power to avert disaster but doing exhausts her and she falls asleep. Before passing out Belldandy tells Keiichi that they should go to a temple just 1 more kilometer away. Meanwhile it begins to rain fairly hard, drenching the couple.

Inside the abandoned temple, Keiichi looks for a way to dry the still-sleeping Goddess. Keiichi rummages  inside his bag and finds a hairdryer. but eventually settles for a blanket. Exhausted and cold, Keiichi passes out. Later in the evening Belldandy awakens to find out that Keiichi have a fever, which she promptly heals. Belldandy then walks outside and casts a spell to restore the  temple to  its original glory. It's morning when Keiichi wakes up. He's concerned about using the temple but Belldandy tells him that she has received permission for them to use it as their home.

Having found a place to stay, the couple buys things to get them through for a while. Unfortunately Keiichi spends all his money, which is a problem because it will take a week to get his next allowance. Belldandy tells Keiichi not to worry as good news would head his way soon. Realizing that he'll be living alone with a good-looking woman, Keiichi starts fantasizing. Keiichi snaps back to reality, reminding himself that Belldandy is a goddess and that there is no telling what will happen to if he will does such thing. Belldandy rises to go and make some tea. Keiichi follows to assist her but he trips over a coffee can and knocks the two of them to the floor, face to face. Gathering some courage, Keiichi begins to make a move but the kiss  never  materializes  as  Megumi,  Keiichi's  younger  sister  steps  into the house. She congratulates Keiichi for living with a  girl  and  goes  on  to explain  that  she'll  be staying while she looks for an apartment. Belldandy's prediction comes true as Megumi also gives Keiichi the money given by their parents for her for living expenses. Moments later Keiichi's dorm buddies appear with food and drinks at hand to celebrate his moving in. Keiichi just sighs as his chance to be alone with Belldandy disappears.

It's evening and the people are still partying. Taking a break from the festivities, the couple sit outside in silence, amidst the moonlight and falling cherry blossoms. Summoning enough courage, Keiichi places her hand on Belldandy's shoulder. It's Keiichi's turn to be surprised as the Goddess rests her head on his shoulder. With a smile, Keiichi contemplates their future together...