Takeuchi later said she planned to kill off the protagonists, but Osano rejected the notion and said, "["Sailor Moon"] is a "shōjo" manga!" When the anime adaptation was produced, the protagonists were killed in the final battle with the Dark Kingdom, although they were revived. Takeuchi resented that she was unable to do that in her version. Takeuchi also intended for the "Sailor Moon" anime adaptation to last for one season, but due to the immense popularity, Toei asked Takeuchi to continue the series. At first, she struggled to develop another storyline to extend the series. While discussing with Osano, he suggested the inclusion of Usagi's daughter from the future, Chibiusa.