User blog comment:GoDai/Translations for everything you can think of./@comment-4076672-20120615094216/@comment-1926430-20120616073514

I guess so. Clearly "to be worthy" isn't all about power, unlike what most characters seem to think. Baam may just be too damn dangerous, as with Phantaminum and Enryu and the like.

I still think Rachel is definitely an Irregular, as Headon never chose her.

It's just my own theory that sometimes, the Tower itself may want someone to enter and climb it, without being selected by Headon. Why does this happen? Possibly for reasons beyond human comprehension.

Besides, it's still a debate topic over at the official fan cafe, so I'd say SIU still hasn't told us enough yet, on purpose.