This is genius despite being rated somewhat lowly. It's probably because the punchline does not give the same effect unless you know what they're talking about.
If you didn't read the note left by the translator at the end, Natsume Sōseki is a Japanese novelist in which one day overheard a student confessing very awkwardly by saying "Ware Kimi wo Aisu", which is a very direct way of saying "I love you" which did not fit the current times of the Meji Period as feeling(じょう)(Jou) was more commonly used than love(あい)(Ai) as it was too direct and rejected Japanese sensibility.
Believing that it should be said in a more subtle, yet fashionable way. Thus, the term "Tsuki ga Kirei desune" was born which translates to "The moon is beautiful"
Not many of Western readers will probably not get it, but the sentence is quite famous in Japan and is often used to confess. The manga subverts the expectation of the reader believing the male student to say the line, but instead directly said what was in his mind. The manga isn't great and there's definitely better one-shot mangas, but I totally agree with the previous commenter for despite its short content, its hilariously genius.