When they say 7 keys, they show you 8 images because they are 7 keys + the box that is Hachimaru.
Hachimaru is no longer a key if not the box itself, so there are now only 7 keys to open it. Ann is just protecting Hachi.
For me the best episode of the week to Chainsaw, by the way does anyone...
Certainly, although the pace had increased in the last chapters, when reading chapter 42, Kishimoto continues to add new information that seems to have to be relevant for later.
It also does not help that they announce that the series ends just when they publish the last chapter, without prior...