Also known as: 星野光
One of the Sailor Starlights who are looking for Princess Kakyuu. Seiya is the black-haired member who gains feelings for Usagi, even though she is waiting for Mamoru to return from America. Seiya transforms into Sailor Star Fighter. The treatment of the Sailor Starlights radically differs between the original manga and the 90s anime, with the trio being able to transform into men in the anime when this did not exist in the manga.
She is voiced by Niiyama Shiho in the 90s anime, and by Inoue Marina in Bishoujo Senshi Sailor Moon Crystal.