The last arc pulls off the impossible: it lets you say goodbye to something you loved, then gives you a reason to keep watching. Usagi losing Mamoru forces her to become the hero she always was without needing to be saved, and the Three Lights arriving as Sailor Senshi isn't a replacement, it's proof the story was never about one person. Galaxia is the first villain that actually feels like the end of something, not just another arc to survive.

The season unfolds in two arcs. In the first, the Outer Senshi Haruka, Michiru, Setsuna and Hotaru return, Hotaru now reborn as a child, while loose ends from the previous season are settled and Queen Nehellenia resurfaces. In the second, Usagi says goodbye to Mamoru as he heads to America to study, and an idol trio of three boys, Seiya, Taiki and Yaten, known as the Three Lights, appears. A new enemy, Galaxia, seeks to rule the whole galaxy by gathering the Star Seeds of humans. Three new warriors, the Sailor Starlights, arrive with their own reasons to oppose her and intend to do it without Sailor Moon's help, while searching Earth for their lost princess. The mix of action, comedy, drama and romance fits this magical girl fantasy.