Finally watched Jujutsu Kaisen 0 after getting into season 3 and the ending kind of wrecked me. Gojo straight up kills Geto at the end, even though Geto's already dying from his fight with Yuta and Rika and i don't get why he didn't just let the higher-ups handle it, or try to save him instead. Were they really that close as friends, or is there more going on there?
i think it's less "why didn't he try to save him" and more that gojo genuinely believed there was nothing left to save, and that killing geto himself was the kindest version of a very cruel situation.
geto's already dying when gojo shows up, so this isn't really gojo choosing death over rescue - it's gojo choosing to be the one who does it instead of letting the higher-ups take geto in. and jujutsu society is not gentle with people like geto. handing him over alive just means a slower, colder ending at someone else's hands, probably after being studied/interrogated first.
and yeah they really were that close. the "you should at least curse me at the end" line right before it happens is doing a lot of work - akutami actually confirmed in an interview what gojo mutters right before that cut, and it's the same line from their student days: "my best friend did. the only one i have." present tense. he still means it, even then.
there's also a nasty little twist later that recontexualizes the whole scene but doesn't undo it: because gojo doesn't cremate the body afterward, kenjaku is eventually able to take it over and wear geto's face for basically the entire rest of the story up through shibuya. so the geto you see in the main series after 0 isn't really him anymore - but the geto gojo kills IN zero is still really him. that part's not a trick.
so no, not arrogance, not "letting the adults handle it." it's a mercy killing dressed up as an execution, from the one person who still loved him.
gonna be honest, the movie never actually shows us what Gojo says to Geto in that final scene - the dialogue's deliberately withheld, both in the film and the manga chapter it's adapted from. so anyone giving you a word-for-word "here's exactly why" is filling in blanks the same way the rest of us are.
what we do get is the reasoning underneath it. Geto, even while dying after losing to Yuta and Rika, never recants - he's still committed to the "wipe out non-sorcerers" plan right up to the end. so Gojo's not really weighing "save my friend" against "let the system handle it," because Geto's made it pretty clear there's no version of him getting handed over that ends with anyone changing their mind. the higher-ups taking him alive just means a body (and a genuinely absurd stockpile of collected curses) sitting around as a liability, possibly weaponized by exactly the kind of people Geto hated in the first place.
so it reads less like "Gojo kills his friend" for no reason and more like Gojo refusing to let Geto's death be someone else's tool - doing it himself is the last thing he can actually control in a friendship he'd already lost long before this fight. doesn't mean they weren't close, if anything the fact that Gojo's the one who does it is what makes it land as a mercy instead of an execution.
anyway that's the reading most people land on, myself included, but since we never get the actual words spoken there's always gonna be room to disagree on the emotional math here
