One of Tenma's close friends, Eri's father is British and her mother is Japanese. She has great difficulty with Kanji. Eri is extremely wealthy and somewhat spoiled (Western Europeans in Japan are stereotyped to be billionaires and extremely snobby). Eri is devoted to her father, but cannot spend as much time with him as she wants because of his work commitments.
She is attracted to Harima, becoming very jealous and angry towards anyone rumored to date him. This even causes some strains in her relationships with Mikoto and Yakumo. Eri was unaware of Harima's true love interest for a long time and came to the realization on the night of her birthday party. After witnessing his happiness whenever he is alone with Tenma. Even so, they do a fake marriage on paper for her family status at the end of the manga and is constantly seen with Harima, implying a possible relationship.
In "School Rumble Z" she works as a stewardess and still seems to be looking for Harima. In the last chapter, she is seen walking into Karasuma's hospital room with Harima, while holding a baby. This presumably refers to that she has gotten married with Harima.