Exstetra for PS Vita and 3DS releases on October 17th 2013 in Japan.
Miko Serene is a priestess of a village at the foot of the tower. She helps protagonist Ryouma who suffers from amnesia find his way around Amasia.
Mizuki is one of the knights of Prisma, who is destined to save the world. Back in the real world, she was into archery and seems to know certain key things about Ryouma before he suffered memory loss.