An older man who works in the literary field, one day faces an accident involving a bicycle, that occurs because of a young student, who wasn't paying attention. Since the student is poor, he offers to help the sensei with his work, till his right hand heals and he's able to work properly. Slowly but steadily, we see love (and lust) blossom between these two couples.
I mean sure, you have the young and eager het student who falls in love with his mature, stoic and gay sensei. But the *real* reason you should read this recommendation is bc it too has a Levi doppelganger who looks gorgeous when he wears glasses.
And older/mature writer ends up falling for a student much younger to him. In both stories, it's the student who confesses his feelings to his sensei first. But this is where the similarities end, as both manga treat their topics very differently.
A dark haired, bespectacled and mature writer feels lost in life because of his inability to produce good literary works. However, one day, by sheer coincidence he runs into a light haired and innocent student, who helps give inspiration to our writer.