Sasami has been chosen by candidate queen Tsunami as champion of justice "Magical Girl Pretty Sammy" with Ryo-Ohki as her guide. Meanwhile Tsunami's jealous sister Ramia has her brother Rumiya turn Sasami's best friend Misao into the chaotic "Pixy Misa". Pixy's first attack is to intensify a love triangle between Ryoko and Ayeka for Tenchi's affection by turning the two quarrelling girls into love-love monsters. With Tenchi's help, Pretty Sammy is able to dispel the love-love curse from the girls.

Biff Standard the greedy US entrepreneur of SynchroniCity is plotting to incorporate his business into Japan aided by Ramia. Pixy spreads the SynchroniCity program into computers all over Sasami's home town. The Standardisation power attracts the moon towards Earth. With Miss Washu's programming, Pretty Sammy is able to put Biff's software off line, cure Biff of his mania and save the Earth from colliding with the moon.

A comet has landed in Japan, where Tsunami and her family and family happen to be going on vacation. Ramia has gone missing has turned into an amnesiac. Washu analyses a sentient blob of cosmic slime that was found at the comet crash site. Misao is attacked by a sorcerer, who overwhelms Pretty Sammy the next day. Makoto and the sorcerer are revealed to be transformed cosmic slimes. With Ryo-Ohki and Pixy's help, Pretty Sammy defeats the sorcerer, which restores Ramia's memories.