Hmm. Chapter 0 talks about serialisation being released in a monthly magazine. 8 to 13 pages per chapter for a monthly released manga is tad bit of a middle finger, especially if the fan-service is kinda tame for a gooner manga. Will this boil down to low number of pages, one maybe two decent "shots" of her thighs, and her ASMRing something to him along the lines of "pervert" each chapter?
Yeah I'm noticing that a lot and while it is nice it does also get old if you keep repeating the same thing especially with such a small number of pages. I think mangaka are either getting lazy or embracing a healthy lifestyle to an extreme degree where they're not actually doing much work and releasing the .1 .2 chapters and so on
From an armchair psychology point of view, one might imagine the dude would simply enjoy any and all interaction with the classmate he admires. So, be it insults or anything, if she pays attention to him and talks to him, he will like it. However, if he starts enjoying being insulted by his own sister, then he should become concerned about his mental health.