Maru is a Maronian, a being from the distant planet Maron, and serves as the devoted attendant to Prince Meru. She first appears as an antagonist, working alongside Meru to kidnap Natsumi Hinata, whom Meru has chosen as his bride to help rebuild the lost Maronian civilization. Maru is highly capable and physically strong, demonstrated when she easily defeats Giroro in combat, showcasing her skills as a formidable fighter. Despite her initial role as an adversary, Maru is not inherently malicious; her actions are driven by loyalty to Meru and a shared desire to restore their home world. She is protective of Meru and initially treats Natsumi with suspicion, viewing her as a tool for their plan. However, as the story unfolds, Maru’s personality reveals deeper layers. She harbors unspoken feelings for Meru, which Natsumi notices and encourages her to acknowledge. When Meru becomes corrupted by the power of the Mer Ball and loses control, Maru shows her true allegiance by guiding Keroro and Fuyuki to him, risking herself to help save him. In the climax, she is absorbed by the unstable dream world but is rescued by the combined efforts of the Keroro Platoon. After the crisis resolves, Maru and Meru come to realize their mutual feelings. Natsumi symbolically passes the title of princess to Maru, and the two Maronians depart together in a ship to return to Maron and marry, having grown from lonely exiles into a couple ready to rebuild their future. Maru’s background as a Maronian with no memory of her home planet (as suggested in some accounts) adds a layer of lost identity, which is resolved through her emotional journey. Her notable abilities include superhuman strength and combat prowess, as well as access to Maronian technology such as the Mer Ball, which she uses in conjunction with Meru to create an underwater dream world from Natsumi’s memories. Throughout the film, Maru evolves from a secondary antagonist to a key ally, finding her own voice and embracing her role not merely as a servant but as a partner.