Louis Asahina is the eighth son of the Asahina family, though it is later revealed that he was adopted by Miwa Asahina. He works as a professional hairdresser and takes great joy in styling hair, particularly Ema Hinata's. Louis is known for his calm and mellow demeanor, speaking in a relaxed, slow-toned voice. He often appears lost in thought, gazing up at the clouds, and can seem unaware of his surroundings, yet he is perceptive about the feelings of those around him. He is one of only two people who can communicate with Juli, Ema's pet squirrel, and he promises Juli that he will protect Ema. Louis is also part of the Protect Chi Club, a group formed among the brothers to look after Ema.

His personality is gentle and considerate, making him a reassuring presence among his brothers. Despite his reserved nature, he possesses a competitive side that emerges during classical music performances with his brother Subaru, as Louis is a skilled violinist with a deep appreciation for the arts. His motivation stems from a strong sense of family; he believes that family is defined by love rather than blood, a sentiment he shares with Ema when he kisses her gently on the cheek. Throughout the story, Louis develops a closer bond with Ema and becomes more open about his feelings, while maintaining his characteristic tranquility. His notable abilities include his talent as a beautician, his violin playing, his unique connection with Juli, and his keen emotional perceptiveness.