honestly despite how much shit it gets i think the whole manaria arc isn't entirely horrible, there's setup with really great potential. it's just that the actual ending was absolutely fumbled.
the arc was focused primarily on exploring how rei just automatically accepted that she would have to settle for being at claire's side while watching her find happiness with somebody else, and how she's afraid to actually confront her feelings for claire. even though she's very open about them, it's rarely in a serious way and she never really takes the time to just sit down and be emotionally open about her romantic feelings for claire without any jokes involved (and it makes sense why she would be afraid of that considering how horribly things went the first time she confessed to another girl). instead, she just settles for being at claire's side to support her even if that means she has to bear the emotional weight of seeing someone she has feelings for find happiness with someone else, which is a very unfortunately common lesbian experience. she's avoiding the hurt that would come from rejection by staying as a spectator, because even though refusing to participate as a genuine contender in claire's love life means she can't win, it means that she can't really lose either. it's why she mentions that for some reason it feels so much worse seeing claire's affection directed towards another girl: if the only options are men, it means she isn't being chosen because she was never an option, but if the options include women too, it means she isn't being chosen because claire is actively choosing someone else over her.
the characters describe this whole mindset as rei giving up or having half-baked feelings for claire, which i do think misrepresents the intended meaning and comes uncomfortably close to seemingly like the characters are trying to say that true love is completely ignoring someone's boundaries. but the conversation in ch. 24 with manaria makes the intended message more clear- in manaria's case, she tried to do the exact thing rei did by not confronting her feelings while staying by the side of someone she loved and eventually the emotional weight that had on her got so bad that she literally became a sexual predator which is... certainly a writing choice, but the point is that she bottled up her feelings for so long that she reached her emotional breaking point and did something messed up and irreversible instead of just being honest with her feelings. which is why she's so insistent on pushing rei to not make the same mistake (to the point of literally threatening to rape claire, i guess).
it all concludes in chapter 25, which is where the real fumble of the arc is. the resolution i very much expected was that rei, after spending hours fighting monsters and grinding for a rare item, would end up with nothing to show for it besides a literal random tree branch, but because she put so much time and effort into trying to find something for claire, the tree branch would end up having more emotional weight than manaria, who just used the generic best choice. it would have tied things together fairly well, imo- it'd make for a nice parallel to rei's duel with manaria, where she tried her hardest at doing something that seemed impossible and it ended in failure. instead, she would be trying to win a fight that should theoretically be impossible (using a literal random tree branch against the proven most effective choice for the scales), but because of the amount of care she has for claire, she succeeded, showing that success is possible even when doing something that seems impossible (which rei initially thinks is the case when it comes to claire actually reciprocating her feelings) and that it isn't worth giving up without trying just because you think failure is guaranteed (which is exactly what rei does in regards to claire). and not only that, but having to use an actual random stick for the scales would be forcing rei to confront the feelings she had been avoiding, since she'd have no way of knowing whether or not the tree branch would actually work, and would have to just accept and trust that she has so much genuine love for claire that no matter what she places on the scales she'll win.
but instead of that, the resolution we got was... rei uses her isekai video game knowledge to metagame and get an auto-win rare drop that turns into a massive tree that's just heavy as fuck rather than having emotional weight. ok.
