Talk:Special Investigation: Jurakutei/@comment-35177215-20181102113819/@comment-70.35.211.4-20181102124008

After you defeat the boss there's the option to retreat, at which point your party returns to the Citadel and you can do other stuff with them (they cease to be locked down inside the event). You can then resume from the post-boss check point with any party of your choice, so yes it's possible to change your team up without losing progress. I'm presonally at the Interior right now, and withdrew my team after the boss in Outer Capital and Inner Capital.

To get the new sword you need to clear out 300 enemies before finishing the final boss. 20th reward, do you mean on the 20th boss clear? The page has been updated, the 20th final boss clear grants a Letter Set.