Mortal Shell: Enhanced Edition

There are 7 seeds you gain through successful completions of the virtuous cycle. Make sure you don't turn them all in before you get this as I'm not sure if you can get more and turn them in once you hand over the 7th seed because your sister will no longer be there. I initially thought this was just beating the cycle and earning a seed as Hadern and panicked when it didnt unlock, thinking it was glitched. But the requirement is actually simple. I remembered the shells are down below in the crypt of the tower/hub in the campaign so I looked and there they were. Grab Hadern and then talk to your sister to turn in a seed. Achievement unlocked.