The Kashima Sister(Gakuen Babysitter Fanfic)

What if Ryuichi and Kotaro have a sister?

Aina Kashima is the middle child of the Kashima siblings. After their parents died from an airplane accident, they are left orphaned and having no place to call home. That is until the chairwoman of the prestigious Morinomiya Academy offers to take the siblings into her care, giving them a new house and free tuition, but there's a catch:

Ryuichi and Aina must help out with the school's daycare center while attending normal classes during school hours. Ryuichi and Aina soon met and became friends with the stoic and blunt student, Hayato Kamitani, but what Aina falls for him?