Roselle Gustav is a Transmigrator from the modern era. He follows the Savant pathway. He transmigrated in the year 1143, over two hundred years before Klein Moretti. Roselle was responsible for bringing over a lot of proverbs, literature, and advancements in technology. He is a major source of knowledge and help for Klein who uses Roselle's diary entries to learn more about the world he has transmigrated in.