One day at Tomoeda School, Sakura, Tomoyo, Rika, Naoko and Chiharu are talking during lunch about how great their school is. Sakura is excited about swimming class until Chiharu points out those strange things have been happening as of late in the school pool, that "something" pulls on people’s legs. Sakura becomes frightened.
However, in swimming class Sakura becomes convinced that there is nothing wrong and she gets to swim. Suddenly she hears a noise and turns around to see Chiharu start to drown. Sakura goes to her rescue and sees a small whirl pool constricting her leg. Sakura grabs the spinning whirlpool and pulls it apart, freeing Chiharu from its grip. Sakura then tries to swim back up to the surface but faints. She wakes up and finds everyone crowded around her. She asks who rescued her and Naoko and Rika point to Tomoyo, who smiles.
At Sakura’s house, Sakura talks with Kero and feeds him a piece of a pancake. He suspects the phenomenon could be a Clow Card. Suddenly Toya arrives home early. Sakura quickly ushers Kero to go and hide in her bedroom, and she throws him up the stairs. Sakura welcomes her older brother home, and Toya takes a pancake and eats it. Sakura becomes cross that he ate the pancake she made without her permission. Yukito is also there and Sakura offers to make them some more pancakes. As Sakura carries the plates of pancakes and drinks to Toya’s room her hands aren’t free to open the door. Yukito suddenly opens the door from the other side and helps her. Sakura is surprised and asked how he knew she was there. He simply replies he had “a feeling,” she was there.
Sakura goes to her room and shuts the door behind her, and slides along down it. Kero asks her what’s wrong and Sakura hugs him, tightly: she’s happy about Yukito. Kero quickly reminds her of her duty as a Cardcaptor. He tells her the card in the school’s pool is the Watery, an aggressive Clow Card with a temper. Kero also tells Sakura she doesn't have a card that can defeat it.
In cheerleading club rumors persist that accidents are still occurring in the pool and it could be closed down. Sakura doesn’t want that to happen, but she doesn’t know how to capture the Watery. Yukito arrives and invites her to eat snow cones after school as a thank you for yesterday’s pancakes. This gives Sakura an idea on how to capture the Watery.
At night, Sakura and Kero arrive at the school’s pool. She uses her new cell phone (lent by Tomoyo) to call Tomoyo and asks her if all is ready for the capture. Sakura then lures out Watery, and uses the Fly to evade and lead it around the school and down the flights of stairs. The Watery is close behind, pursuing her. Sakura heads towards the school dining hall freezer and traps the Watery inside using Windy to help speed up the freezing. Sakura opens the door to find the Watery now a frozen statue and is able to seal it away.
- Sakura Kinomoto
- Tomoyo Daidouji
- Toya Kinomoto
- Yukito Tsukishiro
- Chiharu Mihara
- Naoko Yanagisawa
- Rika Sasaki
- Yoshiyuki Terada
- Kero (Cerberus)