Arisa revolves around Sonoda Arisa and Uehara Tsubasa, twin sisters separated by their parents' divorce who promise to send letters to each other to keep in touch. They finally meet again for the first time after three years. Tsubasa is envious, but proud, of her sweet, popular sister, in comparison to her own school life where she is often referred to as The Demon Princess' and Arisa suggests they switch places for a day. But their swap exposes a dark secret in Arisa's life - one that Tsubasa must solve. In Volume 2, a mysterious King arrives to control the class...'