Queen Serenity, Principess Selene in the Italian animated adaptation of Sailor Moonis described as one of the most powerful beings in the universe. Why do princesses risk their own lives to defend it?
Technically, the Sailor Warriors are not supposed to protect the royal family of the moon, just those of Protect the solar system and the respective home planet. Why are you risking your own safety to protect Regina Selene? The answer is pretty trivial, Mangaka Naoko Takeuchi wrote each of Sailor Moon's storylines as if it were the last, which resulted in multiple plot loopholes. But there can also be a deeper answer.
In peacetime, the Sailor Senshi did not have to fight, so they were hired guard the young princess Serenity, reborn on earth in Bunny (Usagi). In addition, since their crystal is extremely powerful, the warriors protect the royal family much more than the crystals of the surrounding planets.
During the saga, it was found that the various sailors are daughters of gods: For example, sailor Pluto is the daughter of the Greek god of time Chrono. Hence, the gods may have simply imposed on their offspring defend the queen. What do you think about it? Is it a narrative hole or do these hypotheses seem credible to you? Sailor Pluto is Sailor Moon's strongest warrior. What happened to Bunny's parents? Let's find out the truth about the family of the main character of Sailor Moon.