Genkai JK Kirimi Sanjuuni-sai

Story

Keigo Kazami (28) is a high school teacher with a thing for older women. One day, he finds himself with a new transfer student in his class: Kirumi Takanashi (32), a famous actress and mother!? Kirumi had been urging her truant daughter to attend school, but when her daughter pointed out that Kirumi herself never finished high school due to her acting career, Kirumi declared she'd go to school first—and she fills out that uniform quite nicely! Keigo is flustered by the older student in his class, but the principal asks him to help make sure Kirumi has a “fun” high school experience…

Synopsis via AniList (English).