I will prefer if Harumi hits her sister instead who is better and hotter than Matsuri but sure is complicated that why she got for the blondie instead
I kinda cringe with incest but I feel like she even has a better chemistry with her sister than Matsuri.
Harumin's words about Matsuri didn't make any sense, and it feels like Saburuta was trying to make it seem like something deep, but it turned out to have no consistency and be more random.
It just seems like author wants to find an excuse to extend the story as much as possible, because she never had any development between them to begin with. Saburuta isn't very strong with chemistry developing, like we can see with Mei and Yuzu, but Harumin and Matsuri don't just have zero chemistry, but negative. At least in my eyes.