Takahashi-kun wa Miteiru.

Mamoru Takahashi, a freshman in high school, has a woman on his mind. It is Aya Narumi, a teacher with gorgeous looks and impeccable style. Mamoru suspects she was his childhood friend from a long time ago. One day, Mamoru finds a mysterious app called "Nozokimi App," which allows him to see the true feelings of the opposite sex. He uses it on Aya to see if she really is his old childhood friend, but what will he see when he tries to peek into her heart...?

(Source: Comic Gamma Plus, translated)