Moyuru Haru ni Deau Bokura

Haru Takanashi, a plain and unassuming boy with black hair and glasses, secretly has a crush on Nanjou, a popular teacher. This crush is accidentally discovered by his classmate, Kazuki Sanada, a flashy and popular guy who is the complete opposite of Takanashi. Sanada takes an interest in Takanashi's unrequited love for Nanjou and tries to help Takanashi attract the teacher's attention. But as Takanashi starts spending more time with Sanada, he begins to experience Sanada's kindness... Maybe Sanada isn't just the flashy guy he appears to be...? What will become of this usual pairing...!?

(Source: AlphaPolis, translated)