|Age||15 (First year)|
16 (Second year)
|Hair Color||Blonde (manga)|
|Education||Attending Sainan High|
|Unusual Features||Very close to Arai Sayaka|
|Manga Debut||Chapter 17|
|Anime Debut||OVA 1|
Koyomi Shirayuri (白百合 こよみ) is a minor character, the classmate of Yūki Rito in both his first and second year. She is often seen hanging around with Arai Sayaka. She and Koyomi are Sairenji Haruna's fellow members of the tennis club. It is strongly implied that she is in love with Sayaka.
Koyomi has brown pigtails and brown eyes in the manga (black hair in the anime).
Koyomi has very little involvement with the plot, though she is one of the more significant named minor characters in Sainan High. Most of her appearances are for fanservice sake.