Kodomo x Otona no Houteishikiこども×おとなの方程式 ; 小孩×大人的方程式

Nanjou is a divorced father with a child, Chiharu. Chiharu's teacher from the childcare center, Aiba, ends up staying at the Nanjou family's place to take care of Chiharu as his 'mom.' How does the relationship between Nanjou and Aiba progress?