Chibiusa was Mamoru and Usagi's daughter from the future. In the future, Chibiusa respected and adored her mother, but in the 20th century, she and Usagi had a relationship more like squabbling sisters than mother and daughter. Usagi also met her past-life mother Queen Serenity, or at least her spirit, and loved her dearly; they did not have a strong relationship, though, as she was mostly confined to within Usagi's subconscious mind (in the anime) or the Moon Palace computer (in the manga).

In the story "Parallel Sailor Moon," she and Mamoru had a second-born daughter named Kousagi Tsukino.