Princess Romina Ladorio, heir to the throne of the distant galactic planet Ladorio, is approximately fifteen to sixteen years old. She possesses striking silvery-lavender hair styled in a bun beneath her tiara, blue eyes, and a slender frame. Her peaceful homeworld faced devastating invasion and occupation by the Zaboom army, leading to the death of her father, Ladorio VII. Fleeing the carnage, she escaped with her attendant Jade and the general Icelander aboard the spacecraft Xenos 5, also known as Ellshanc. They embarked on a critical mission entrusted by her parents: to locate Earth-born pilots possessing the unique innate ability to operate Ladorio's three specialized ninja robots, essential weapons against the invaders.

Deeply grieving her lost parents and homeland, Romina often reveals profound sadness and vulnerability in private. Publicly, however, she maintains a modest and sincere demeanor, projecting courage and resilience as their leader. Her loyalty to Jade and Icelander is absolute, and she demands equal commitment from them. Crash-landing on Mars within the Milky Way, she encounters teenagers Joe Maya, Mike Coil, and Jenny Ai, who unexpectedly prove capable of piloting the ninja robots. Romina convinces them to join her mission, offering escape from Martian oppression in exchange for defending the Xenos 5 and journeying to Earth to seek legendary ninjas.

Her relationship with Joe Maya evolves significantly. Joe is immediately drawn to her, acting protectively and impulsively on her behalf. While appreciating his dedication, Romina grows troubled by the escalating conflict this sparks between Joe and the affection-driven Icelander. Gradually, she develops genuine romantic feelings for Joe, repeatedly risking her life to save him. This creates tension with Jenny, who openly loves Joe. Romina eventually confesses her feelings to Jenny, forging a truce where both prioritize liberating Ladorio before confronting their romantic rivalry.

As a leader, Romina demonstrates increasing resolve and diplomatic skill. She negotiates sanctuary and aid from Earth organizations like the JUDA Corporation, leveraging historical ties between Ladorio and Earth's ninja heritage. Her commitment to liberating her planet remains unwavering, even amidst betrayals like Icelander's temporary defection to Zaboom for power. In the final conflict, she witnesses Icelander's mortally wounded return and his ultimate sacrifice to power the Xenos 5. Following Ladorio's liberation, Empress Romina dedicates herself to rebuilding her world while sustaining vital connections to Earth and its allies.