Aren't you his mother

Sinopsis

Because of Shin's scary story, Yankumi is scared to walk alone to the school hallway. One time she left her phone and thinks that someone was following her only to find out that it was a little boy. The boy was Yuta Nakashima-sensei's step son. The boy think of the Nakashima as her mom but since they aren't blood related, Nakashima thinks they are not. How will Yankumi give Nakashima her senses?