Schoolgirl's Feelings!

I agree. In this case, I was merely pointing out a popular sub-trope.
As I commented on another chapter:

The Teenage Schoolgirl is the CENTRAL ICON of Japanese porn.
She is the pillar upon which all hentai rests.

As you note, for the Japanese, high school is (supposedly) the pivotal
period of their lives, a Golden Age of Happy Memories which, however,
has no connection with reality.

According to everything I've read and heard, Japanese high schools are awful---
grim bastions of boring conformity and strict regimentation where individuality is
ruthlessly crushed, and where students are cruelly bullied, by their teachers as
well as their classmates. Sexual assault (as a form of bullying) is not uncommon.
For example, an unpopular girl might get dog-piled by other girls, who jam inani-
mate objects into her anus and vagina.

On top of that, the students are under constant pressure to get good grades.
Academic performance is everything. Japan is the most class-conscious country
in the world, and your social and economic status depends almost entirely upon
your grades (unless you're lucky enough to be born into wealth and power).

If your marks are poor, you are forever doomed to a life of low-paying jobs
and cheap, shabby apartments, with all the attendant social disadvantages,
like severely-limited dating and marriage options. Hence, the prevalence of
cram schools (and suicides).

The fact that so many Japanese look back on their school days with such
rose-colored nostalgia is a testament to the power of pop culture, which
has wildly romanticized (and sexualized) the grim reality of the high school
experience in Japan.

Note:
Japanese students who spend several years abroad in foreign schools
(where they're usually treated kindly) are often shocked when they return
home to a brutal Japanese school, where they find themselves being bullied
and treated like dirty gaijin (even if they're native-born, full-blooded
Japanese). God help the kid who has picked up even the hint of a foreign
accent.