In Edo period Japan (1603 to 1868), a strange new disease called the Redface Pox has begun to prey on the country's men. Within eighty years of the first outbreak, the male population has fallen to a quarter of the total female population. Women have taken on all the roles traditionally granted to men, even that of the Shogun. The men, precious providers of life, are carefully protected and the most beautiful of the men are sent to serve in the Shogun's Inner Chambers.

Arusu believes in magic. With all her heart, she believes that magic is possible and that it can be used for good deeds and fun games. But suddenly, she finds herself transported into another world, ruled by a mysterious elite of witches—and these witches don't seem to be in it for the fun. They're hard at work capturing sprites, the native magical beings of the world, and forcing them into slavery. Once Arusu realizes that her new surroundings aren't just a dream, she sets out to change things. (Source: ANN)

An OVA summarizing all 25 episodes of season 1 from Lelouch's viewpoint.

After a successful showdown at Tokyo Tower, the Mew Mew girls enjoy a temporary respite. Now that Ichigo Momomiya and Masaya Aoyama have confessed their feelings to each other, Ichigo is overjoyed to spend time with her new boyfriend. However, their quick break gets interrupted, and soon the girls must battle against the Chimera Anima yet again. When things go awry in the ensuing fight, Ichigo is placed in grave danger. Just when things look most bleak, the mysterious Blue Knight arrives and saves Ichigo, proclaiming that he was born to protect her, before disappearing into thin air. With the fate of the world on their shoulders and the identity of the Blue Knight in question, the Mew Mew girls must strive to create balance between alien-fighting and their personal lives.