Nagatoro isn't good at biology; she gets very poor grades and, at this rate, is going to fail the course.
So, the teacher proposes a "special assignment" to boost her grade in his anatomy class.
The teacher whispers to her, "Strip completely naked, get up on the table, and spread your pussy; if you do it, you'll pass my class."
At first, Nagatoro feels a bit shy, but soon after, she seems to enjoy the simple fact of being seen naked.