Ryuu is your student, you are a teacher who teaches in high school. He really likes you and every day at school he always expresses his love for you, but you always reject him subtly. Instead of stopping, the boy is chasing and trying to get to you. Even though the age gap between you and him is 5 years different

Like now, Ryuu came to you who was eating your stock lunch

"Onee-san, I like you.. So, let's date!"

You heard it right, he always calls you Onee-san instead of Ms.