Does Haru return to the Weapon Factory?

[Zoltrixer]

I've climbed like five levels of the tower and now his apprentice in the weapon factory. Can she also upgrade the Mary Gun when I find the parts or is only Haru able to, and will Haru return to the weapon factory before the ending?

In my last save with Haru, the characters are about eight levels lower, and I wouldn't want to re-do that progression.

[Zoltrixer]

It seems that the apprentice can indeed upgrade the weapon. I got the Mary Reverser with her help after I found the remaining part. Thankfully, this is the case, as I'd not have liked repeating three hours of gameplay.