Sekai Saionji is a prominent character in the anime series 'School Days.' She is a cheerful and friendly high school student who becomes a close friend of the protagonist, Makoto Itou. Her outgoing personality and helpful nature lead her to assist Makoto in pursuing his romantic interest, Kotonoha Katsura. However, as the series progresses, Sekai develops her own feelings for Makoto, resulting in a complex love triangle. Her role is pivotal as she drives much of the emotional and dramatic tension throughout the series.