It's pretty disheartening to hear if they're that common@permisan Perhaps in the West, but in Japan and some other parts of Asia such gadgets have been widely distributed for many years.
tbf I don't think Kainuma's behavior is being played for laughs cause he's genuinely creepy. I can't say the same for Yoko ("sister") thoughThe "comedy" of these creeps perving on, peeping on, and fapping to Misaki is the only thing I dislike about this manga. Sad, cuz it's otherwise 10/10 perfect.