While Mamoru strives to cheer Usagi up after her failure in the previous battle by offering her invitations to the christening of Kiara, Simba finds himself the latest target of Maleficent and her Death Busters. Due to Usagi's inability to transform, the under-powered Sailor Team struggles to fight off the Daimon hordes and are once again forced to rely on Sailors Uranus and Neptune. When Zira, the Death Buster of this world, proves to be stronger in combat than they are, the two older Senshi leave the Sailor Team to fend for themselves. Meanwhile, Tuxedo Mask and Usagi hold hands after the latter's refusal to escape, and through the power of their love Usagi's darkened Crystal Star brooch transforms into the Cosmic Heart Compact, and she gains the Spiral Heart Moon Rod and, along with it, the ability to finally defeat the new enemy. (Kimba and friends are guest stars in the movie).
Usagi and friends are in the pridelands to celebrate the birth of princess Kiara, daughter of Simba and Nala. After Kiara has grown into a young cub, Simba tells Kiara not to go to the outlands. As Kiara went outside to play along with Rini, Hotaru, Lyre and Kimba, Simba sent Timon and Pumbaa to keep an eye on them. When Timon and Pumbaa gets distracted, Kiara, Rini and the others made thier way to the Outlands and they meet a cub named Kovu, then they got surrounded by crocodiles, but they luckily got away.After they escaped, they are watched by lioness known as Zira, when Kiara and the others were about to play with Kovu, Simba, Sailor Moon and the others came, they become face to face with Zira. When Simba and the others returned to the Pridelands, Simba has a talk with Kiara, Lyre and Kimba for desobying him for going to the outlands, they apologies and Simba forgive them and tells them "we are one". Later that afternoon, Rini and Hotaru apologies to Usagi for entering the Outlands and Kimba asks Lyre, why Simba hates the Outlanders, so much and Lyre said because they are the followers of Scar, Simba and Lyre's evil uncle and she tells Kimba that Scar has killed her uncle Mufasa, Simba's father, she also said Mufasa was like a father to her and Kimba feels sorry for her, Meanwhile Zira plots a plan to kill Simba by using Kovu. After a few years passed, Usagi and the others gathered around to see Kiara as grown up Lioness and wishes her luck on her first hunt, but Simba broke his promise to Kiara and sends Timon and Pumbaa, which leaves Lyre and the others disappointed. Meanwhile Kiara was chasing a bunch of herds, she spotted Timon and Pumbaa, She realised that her father broke his promise and ran off. Nuka and Vitani starts a fire, Kiara started to running. Back at pride rock, Simba spotted spoke and he and the others went out to find Kiara. Kiara was still struggling to escape the fire, when she collapsed, Kovu rescued her and got her safely out of the fire. Zazu and Pauly spotted them and went to find Simba and the others. When Kiara found out the lion was Kovu, Simba angrily rushed up to them, Lyre and Kimba tells Simba to give Kovu a chance and he agreed, but Sailor Moon and the Sailor Scouts still didnt trust him. Later that night, Raye wonders where that fire came from and gets a vision of the outlanders attacking. The next day, Rini, Hotaru, Lyre and Kimba went out with Kiara and Kovu had fun together along with Timon and Pumbaa. When they leave Kiara and Kovu alone with a help from Rafiki the two lions fall in love. The next day Lita tells Rini and Hotaru that she and the scouts trust him, which makes the two girls happy. While Kovu was trying to talk to Kiara, Lyre and Kimba about something. Simba decided to have talk wih Kovu, which makes Lyre and Kimba happy. However, Zira and her followers attack them, but Kovu didn't want to kill Simba, who mange to escape from the outsider attacks. Back at pride rock Kiara, Lyre and the gang spots Simba injured. Lita realises it was Zira and the outsiders doing, but not Kovu. Zira angrily scratched Kovu and gave him a scar for not killing Simba. Kovu returns to pride rock, however, Simba exiles him, which made Kiara and the others upset. Kiara, Lyre and Lita tried to tell him that Kovu isn't evil, but Simba doesn't listen to him. Lita angrily says to Simba, she knew him as a cub and saying exiling someone for doing is the worse thing you have done and she walks away. Before Lyre and Kimba walked away with Lita and the others. Lyre says to Simba you have changed. Kiara on the other hand, left pride rock to find Kovu and the two united lovers are happy to find each other and decided to return to pride rock. Meanwhile Zira and her followers make their way to the pridelands. Simba is disappointed that Kira is gone, then Zazu and Pauly tells him and the others that the outsiders are in the pridelands and began fighting with them. Before Simba and Zira could fight Kiara and Kovu says to end this. Kiara tells Simba a wise king once told her 'we are one' and she tells him the outsiders are like them. A sky's light appeared and Simba realised that his daughter is right. The outsiders decided to go on Simba and the other's side instead of fighting them. Zira tried to attack Simba and Sailor Moon. Luckily, Kiara pushed Zira and together they tumbled down together. Kiara tried to help Zira, who refuses and falls to her death. Now Zira gone, Simba, the team and the outsiders return to pride rock and accept Kiara and Kovu's affection for each other. Together they roared and the animals and the team cheered. Simba hears Mufasa say Well done my son. Which makes Lyre, Kimba and the others along with Rafiki very proud of Simba, the lion king.