hope this helps. the R15 having lesser chapters is most likely because the mature or rated chapters have been removed (you can say they are not that relevant to the plot since they're just purely sex lol)
s1: 25 Chapters (1~25)
S2: 31 Chapters (26~56)
Side Story 7 Chapters
Ohh... alright alright... i was following the mature version but i accidentally read r15 bonus chapters thinking it's side stories n I got spoiled which i didn't wanted ┗( T﹏T )┛
lmaaoo so thats what it is. yes it does happen chapters jumping off randomly to different pages
Shit I can't read this properly.... why TF the bonus r15 chapters messing up with mature version... it's so confusing ヽ(`Д´)ﾉ