The Day I Got A Little Sister.At a local restaurant, Basara Tojo and his father, Jin, wait to meet Basara's new stepsisters, but they are late. After Basara goes to the bathroom to change, he encounters a red-haired girl named Mio Naruse. Mio and her retainer Maria introduce themselves to Basara. The next day, Mio wakes Basara up as part of her service. Basara gets along with his step-sisters well, and takes a family photograph. When Mio goes shopping, she is attacked by delinquents, but Basara rescues her and they escape. Later Jin leaves on a business trip, and Mio asks Basara to leave the house, and it becomes clear that Mio is actually a demon. Maria attempts to repel Basara using magic, but it fails. Basara explains that he is a member of the hero clan and forces Maria and Mio out his house. Jin calls Basara and tells him that Mio is in danger from the current demon lord's plot to take Mio's inherited strength from her father, Wilbert. Afterwards, Mio and Maria are attacked on a hill by an enemy, but Basara rushes over immediately, rescues Mio and states he came back for his family as he shows their family photograph.