Kaede Saito

In the Chobits series, Kaede Saito and Minoru Kokubunji are indeed siblings, but their last names are different due to family circumstances. Kaede took on her mother's surname, Saito, while Minoru retained the family name Kokubunji, which is their father's surname. This situation is not uncommon in Japanese culture, where individuals may carry different last names due to marriage customs or personal choices.