Alfin Reise Arnor is the Princess of Erebonia and the twin sister of Crown Prince Cedric.

The daughter of Emperor Eugent III and the twin sister of the Crown Prince, Cedric. Known throughout the Empire for her "angelic cuteness," she is immensely popular. She attends St. Astraia Girls' Academy in the Imperial Capital, and is the best friend of Rean's younger sister, Elise. She has a somewhat moody and mischievous personality, and sometimes makes bold statements that surprise those around her. Although she finds her kind but timid younger brother unreliable, she tries to support him as an older sister should. She seems to get along well with her half-brother, "a certain prince". The three siblings seem to get along well.