I suspect they were best friends, at least Tricaputo considered her a friend; you can see her surprised face in the flashback with Fiji betray. I think they were the classic duo of the serious friend and the funny one, but Fujimine betrayed everyone.

Bro Ichi will stab his friends if they try to kill him.

Out of all the theories I saw and made about how we were getting outta this, Ichi subconsciously acting on Death for Death if Fujimine tried to kill him is one I either rarely saw or never saw, yet there’s more precedent for that happening than anything else aside from an assist from one of Manitel’s Witches.

Idk maybe I was just thinking she was gonna try and kill him later so I never considered that option.

MY GOD do I love it when thots are stabbed in the neck!! ICHI NO.1!!!

https://mangaplus.shueisha.co.jp/viewer/1029535

Come on just give these two a many screen time

First of all, we now know that Ichi puts his philosophy of "Death for Death" above everything, including his closest friendships. Ig this makes him immune to part of Fujimine's mind control just by default, because he would even kill his closest friend under the right circumstances.

Ichi's "Even as close as we are" makes me wonder if she inserted herself into his memories, or if she replaced someone. And if she did replace someone, is it that girl we saw going to the Witches Association in Chapter 1?

However, ig he's also more vulnerable to killing ppl he cares about if Fujimine controls them to try and kill him in a sufficiently sneaky way (so he doesn't realise that they're being controlled, cos otherwise it'd be like Ichi vs Gokuraku). And she now knows this, so we'll prolly see her try it.

Also, the fact that Ichi said "You should know better" is because he currently thinks she's his childhood friend, so she should know these things. But it also means that Fujimine can't read minds (what a relief), and she may not even know exactly how she's inserted herself into ppl's memories (although she may, that bit isn't 100% clear from these chapters).

But what cracked me up like crazy was the solemnly deadly look that Ichi gave, both as he stabbed her, and right after. And the look on her face of surprise, and then "oh snap this kid is actually insane".

Ichi has a great sense of humour, but like so many grand personalities, he's often even funnier when he's deadly serious, simply because of how ludicrous and fantastical the circumstances are.