The Nekomi Tech Motor Club along with Urd have gone to the Honda Lodge, an old mountain resort, for their annual summer training camp. Upon entering the lodge grounds, Urd and Belldandy feel the presence of something not normal. Belldandy opens the door of the lodge while Urd is ready with a demon exorcism spell. Greeting them at the door is a normal, good looking girl named Chieko Honda, the housekeeper. Tamiya is happy about the appearance of this girl until she is all over Keiichi, acting like she knows him.

In the drawing-room of the lodge, Urd, Belldandy, Keiichi, and Chieko confer over Keiichi's apparent loss of memory. Belldandy inspects Keiichi who swears he doesn't know this girl. In frustration, she produces an old photograph of her and a young man who looks like Keiichi. It is his grandfather Hotaru-no-suke. Taking everything into consideration, Belldandy realizes that Chieko is a shinnentai*. She explains this to Keiichi in private when Chieko comes and grabs him to join the party that has started. When Belldandy comes into the room where Urd is singing for the club, she can't find Keiichi nor Chieko. Grabbing Urd, the two set off to find Keiichi.

In a darkened room, Chieko has Keiichi unconscious on a bed. Parts of her body are in energy form and are wrapping around him as she attempts to get Keiichi to make the same promise his grandfather made. Urd and Belldandy find the room but the door is locked, Chieko promising it will not open. Urd suspects the shinnentai is planning to possess Keiichi, but as Chieko stated, they are not able to get through the door. Instead, Belldandy enters the room through a mirror and Urd through a TV. Chieko screams about them being ghosts as Urd casts an exorcism spell. It doesn't work since this is a shinnentai they are dealing with and not a demon. Chieko promises not to let him go, causing a frustrated Belldandy to proclaim that he is no Hotaru-no-suke, but her Keiichi!

Chieko replies that this doesn't matter because of the promise. It was what kept her alive when she was ill, and what has bound her to Earth after she died. She feels it is destiny that Keiichi is here. Understanding, Belldandy asks what the promise was.

Waking up the next morning, Keiichi is greeted by Belldandy. He recalls nothing of the night before as Belldandy leads him to the basement. There, Chieko is waiting along side a classic Brough Superior motorcycle which she says belongs to him. The bike had been left there by his grandfather who had promised to make repairs to the bike, then take Chieko for a ride once around the lake.

Later as Tamiya puts the club members through exercise drills, Keiichi has a stupid grin on his face as he thinks about the bike. This annoys Tamiya who forces him to do more exercise. Meanwhile, Urd and Belldandy discuss the situation. Urd can't believe Belldandy would trust Chieko, but Belldandy understands how Chieko must feel.

In his spare time at the training camp, Keiichi repairs the bike. Once repaired, he takes Chieko on a ride around the lake. He tells Chieko that the reason his grandfather never returned was that he died before he could come back. Once the ride is over, she gives Keiichi a kiss on the cheek, fulfilling her end of the promise and vanishes. Keiichi decides to leave the bike at the lodge since technically it is his grandfathers and he never fulfilled his promise.

*Manifestation of will in physical form.