>>89338630There's a queue. It's extremely unlikely that those three were the only ones who chose to leave, especially since at least one mole has confirmed to False that multiple others are in the queue, hoping to win the graduation gacha.
Also each liver who turns in a graduation notice has to complete certain tasks before they can actually graduate (unless their contract expires before those tasks are complete). Things like, say, appearing at live shows like the music fest next month, or Nijifes in February. Mika had to do a charity stream before she could get graduation perms.