Board Thread:Questions and Answers/@comment-13442349-20130726072748/@comment-26420452-20131102224208

Once you become a Hollow, you can never become anymore a Plus. That's what Rukia tells Ichigo in chapter 6. A Hollow that looks similar to a human is simply an Arrancar. By removing a part of their mask, they gain a part of their sanity. Anyway, I wonder about Starrk and Harribel. They've never shown any Hollow traits in their personality, that is, they're fully sane.