@Da_Slasher_XD
It might be handle better at the novel, but I'm judging this based on what has been presented on the manga. Second, I don't really cared that much about the other characters in this world, I mostly cared about things that directly involve Hajime. The way I see it, if the manga had taken such a development, it might have ruined the pace of the story, I already felt like it drag a little bit in some parts and having to cut from the main devolvement of Hajime story to catch up on the characters of the heroes party doesn't seem like much fun, even if most of those scene involved Kaori having memories about his time with him in Japan, that could get boring pretty quickly because I don't see that as the Hajime we know now so I wouldn't really care that much. But at last, I guess I would have to read the novel to truly see how it is handle there. Finally, I rarely find stalker characters that enduring and she stalked the old Hajime, but I guess I'll have to wait for more development to see how do I stand on that. Anyway, thanks for your explanation I really appreciate it.
@goodhunter
Ok I'm gonna be honest with you, and I hope you still care about my opinion after I say this, but I'm a huge NTR fan, and I've been called a "lost soul" before because of that. I've read and enjoy way to many NTR stories and read the comments alongside them. And I'm telling you if the positions were reversed, and It was the MC who was "abandoned" by here childhood friend to be part of another men's harem, maybe not you, but I'm willing to bet that a lot of people would also get those NTR vibes. Just picture that story, the Hero is the MC we see him being isekaid and going on adventures with the other members of the party and Kaori, we discovered that she is his childhood friend and that they have always being to getter and he expects them to keep being together in the future because he is fond of here even if it is just as a friendship bond. Then on one dungeon exploration shit goes wrong the MC is powerless and then another dude comes and saves the day, immediately after that after the MC have experience near dead and is all fucked up Kaori decides to leave him and the party to be part of that other dudes harem, he tell her of how he expected them to always be together and she is like "yeaah but I don't, I actually prefer and love this dude over all our years of friendship"; how would you feel about that development? Maybe my initial statement was wrong it sure is not full on NTR but it definitely have those "lost of a loved one to another person" NTR kinda feeling. So my point is that this does not feel natural, maybe I just don't remember but this thing about them being childhood friends and always being together I don't remember being mention before in this manga adaptation; maybe in the novel is handle different. So to me it feels like unnecessary extra conflict to make the Hero party look even dummer and kinda justify Kaori just leaving them on a whim. It could have been kept on the conflict of "Kaori are you sure you want to go with this guy who kill people on a whim" and that might have given Kaori a chance to showcase how she knows more about Hajime and his good side and that is why she trust him and make here character more enduring and makes us remember why we should also cared about here. But instead the focus is put on the Hero and how he wants to still his harem, just to have a scene on how the harem prefers Hajime over the one who was the popular kid in school. But maybe I'm expecting too much from an edgy power fantasy manga.
To be honest, the moment Hajime said "I said I'd protect her... her smile. NO, fuck her." in chapter 5 I said fuck here too and stop caring about here if Hajime don't care I don't care. In hindsight one might argue that he really didn't mean that and was just a fit of rage. and he shows he did care all along. To me that was the birth of a new Hajime, thus new Hajime, new wifus, let the past rot behind along with Kaori, the heroes party and even Japan.