Satsuki Shinonome

Height: 163 cm
Weight: 47 kg
BWH: 85-58-84

Satsuki is Yuuki's main opponent during the student council elections. She is Hazuki Shinonome's little sister. Satsuki is a kind and gentle girl who also loves Yuuki's famous "Oojima Roll", but denies this. She also calls Yuuki "Pekojima-kun".

It is later revealed that she and Hazuki are actually half-sisters and after it is revealed that in reality they are blood sisters.
(Source: Wikipedia)