It's Just a Story About Peacocks.

Kuji Yakurou is a teacher who was cheated on and dumped by his girlfriend because of his "lack of masculinity." Shouldn't the world be gender-free? He is in anguish, and then Akano, a model, influencer, high achiever, and head of the biology department, appears before him and asks him to be the advisor of the biology department. She then begins to explain why "masculinity" is necessary to be popular after all, using the flamboyant feathers of a peacock as an example of "biology"...!