Sarah McDougall (Sara Makudugaru) is Seta's adopted daughter, and initially delights in making Keitaro's life miserable. However, like most of the girls in the story, she eventually warms to him, even if she still calls him a dork.
Sarah's is left for a time in the care of the Hinata House residents by Seta, as he feels that travelling the world with him on expeditions would be too disruptive to her childhood. There, she develops a close friendship with Kaolla Su. Sarah eventually does return to travelling with him after his marriage to Haruka.
She possesses no unusual talents or skills, though she is adept at bashing Keitaro on the head with priceless artifacts. She also has a panda shaped birthmark on her butt, which she avoids showing at all costs.
Sarah's mother was very close friends with Seta, and they were involed in a love triangle with Urashima Haruka. But when Sarah's mother died, Sarah decided to follow Seta to Japan (Sarah is an American), because she had sort of come to call him her father, due to the closeness they have had. Sarah is also very close to Haruka.
Sarah is very protective of her step-father. If anyone tries to go near him, she will go crazy. She also seems like a brat and she makes you want to ring her little neck, but, thankfully, later she is easier to deal with.
She often plays with Shinobu, Su, and Naru's little sister, Mei. In fact, the four of them go looking for Keitaro and Naru during the Love Hina: Spring Special.