This one
Probably because the sequel already existed when this series had its second volume (and this chapter being a tankobon exclusive). To put it simply, it's an extension of chapter 24, which is the ending of the web comic btw (hence 24.1 instead of 25)
Man, as much as I hate the trope depicted in this manga with a passion, I like the way the author build up the story (and the story itself) along with a rather dramatic take on the rotten side of the trope (which I also like). Now then, if the story can get an ending that not involve the sister...
Well, I mean that's the entire premise of this manga tbh, a fluffy life of a married couple, it's not like she has no friends or hobbies, she did mention she has work to do, and her schedule in this chapter show us a glimpse of Haru's life outside the chapters we know (lunch with Nacchan...
There's a lot of spicy stuff that we (the team that do the Vietnamese translation) really want to add into the chapters, in the end, the one in chapter 10 and the last page in this chapter is the least we could upload without turning this into an H-manga ¯\( ͡° ͜ʖ ͡°)/¯
The timeskip is definitely sucks tho, but I would assume that after the couple confessed their love, they went to Natsuki and somehow clear up the misunderstanding.
For Touma's identity tho, the past few chapters already gave some hint to his identity, like
and his action in some of the panel...