Talk:Kara no Kyoukai Collaboration Event/@comment-2607:FEA8:F1A0:C:58C0:1FD6:F026:BC29-20180214121422/@comment-26333303-20180214125335

You only need to complete room 504 (and everything required to access room 504 ofc), to have Shiki join you permanently. Like, you already have the first copy of the servant, it's just not temporary anymore. Getting the other four isn't required, but I don't see why someone wouldn't want to raise her NP level. And the knives are needed to ascend her, and you can't get them outside of the event.