Shimako Toudou

Prim proper and very beautiful Shimako is the most admired of the firstyears. She is the petite soeur of Sat Sei at the beginning of the story and later her successor. Underneath Shimakos quiet mannerly exterior lies a surprisingly strong resolve. However Shimako is perhaps the most gentle of the three girls of her year in the Yamayurikai. In the first season Shimako is Rosa Gigantea en bouton her grande soeur being Satou Sei. In the second season Shimako becomes Rosa Gigantea her petite soeur being Nijou Noriko. Source: Wikipedia