Reimu Hakurei is the Hakurei shrine maiden and, as such, plays a key role in the goings-on of Gensokyo. While she treats everyone equally, she doesn't tend to grow attached to anyone either. Most of the time, she's pretty carefree and lazy, but she springs into action when there's an incident to resolve.
Hakurei Shrine is located on the east edge of Gensokyo, on the border between it and the outside world. It isn't the only shrine in Gensokyo anymore, but it has retained its significance, and the shrine maiden is just as lazy as ever. The shrine hardly gets any worshipers, and the only human visitor of note is a magician who just comes to chat with Reimu. In contrast, the number of youkai that hang around the shrine increases with each incident or disturbance that Reimu resolves.
Reimu is known as the Mysterious Flying Shrine Maiden, even though being able to fly is a common trait among the girls who engage in battles of bullets. However, it could be said that Reimu flies better than anyone, considering that she attained her Fantasy Nature Last Word by going beyond the limits of usual flight. This unrestrained attack grants Reimu the ultimate freedom and leads her to heights unattainable by anyone else. Perhaps it is only the presence of the people around her that keep her from transcending the bounds of humanity.
The interpretations of Last Words are as varied as their users. It's the Spell Card you save until you need it most, the ace in the hole, a battle-deciding secret technique, the ultimate attack, or just a special move... However, there's one thing consistent between every interpretation. If a Last Word is declared, they will be the last words spoken until the battle of bullets is decided.
"Reimu..."
"What's up, Marisa?"
"I don't care if you use that Last Word against anyone else, but don't use it against me, OK?"
"Huh? You talk as if we're gonna seriously battle someday. Why would we ever do that?"