The characters in "Renko" literally mean "Lotus Child." Usami means "Universe" (宇), "Assist" (佐) and "Sight" (見).
Renko is one of the only characters known to live outside of Gensokyo. As such, she has never actually met any of the other characters except Maribel Han, who also lives outside Gensokyo.
To be more precise, her ability allows her to tell where she is by looking at the Moon and tell the time by looking at the stars. Apparently, wherever she is, the time she sees by looking at the stars is the time in Japan.