The entire Masaki household heads to the onsen inn where they have to do repairs from the damage they caused in their last visit, except for Washu and Sasami. While working, the gang notice a ghost wandering about. After a ghost story is told from Yosho, Tenchi has to repair the inn circuit box but is scared from a ghostly touch as he falls into the inn onsen. Eventually, Tenchi and the girls see the ghost. After Nobuyuki repairs the circuit box, the lights reveal that the ghost is actually Sasami. Everyone is relieved for a little bit until Mihoshi notices Tsunami's reflection in the water along side Sasami. Scared from the discovery, Sasami runs off and Tenchi and the girls accidentally trip into the water when Nobuyuki accidentally electrocutes himself making the lights go out.
The gang go into search parties to find Sasami with Ayeka finding her. Tenchi then comes along, but is dragged into a bush by Washu with Mihoshi and Ryoko tied up and gagged to avoid interrupting Sasami and Ayeka's talk. Sasami reveals that she isn't the real Sasami and starts to sob. Tsunami then tells the story surrounding these claims. About 700 years ago on Jurai during Ryoko's attack, Sasami was in a chamber containing the Jurai trees. As she was about to go towards another platform in the chamber, a ship damaged from Ryoko's attack crashes into the chamber and causes Sasami to fall off the platform.
Lying in a pool of blood, Sasami is in Tsunami's tree chamber. A drop of blood falls into a nearby moat which allows Tsunami to sense Sasami dying and the two merge into one being. Sasami continues to sob after this. Ayeka tells her that regardless of what happens to her, she will still be her sister which is told after Washu throws Tenchi out of the bush he was hiding in. Sasami then cries after this news and runs over to Tenchi to hug him instead of Ayeka, much to her embarrassment.
A little later, Tsunami appears to Tenchi and Ayeka telling them that she and Sasami were actually assimilated and would unite into one being when she is an adult. Later on at a cherry blossoms celebration, Ryoko accidentally knocks out Tenchi with her attempted flirting and argues with Ayeka over who is the second most beautiful after Tsunami. Mihoshi attempts to break up the fight, but accidentally pushes the two into a lake.