Sex education using foreskin boy

"Let them know that foreskin is not a bad thing!"

Ms. Asai, a health teacher, decides to conduct sex education
for female students in order to correct
their incorrect knowledge of "foreskin".

So she invites her brother, who suffers from a foreskin,
as a model and begins teaching classes
in an attempt to dispel the bad image of the foreskin.

However, because his male organ was smaller than she had imagined,
she exacerbates the impression of his foreskin
rather than clearing up the female student's misunderstanding