not buying this.
Raki is a lucky accident, he's a human who can fight youma and somehow resisted infection of an unknown source. he's a great experiment subject, that many crazy museum MIB would like to run tests on, but he isn't something that can be reproduced on a major scale (not in the near future, at the very least).

the organization had two directions, one is the twins; the other is the zombies.
maybe they decided that simply abducting twins was too troublesome, so they started 'birthing' twins and threeins of their own, using some sort of twisted egg fertilizing and surrogate mothers to create 'chains' of twins.strings of girls in the same age with the same genetic makeup, that can all entrust their 'reason' into one twin in a far away location (brain in jar) and have several awakened beings working together without the threat of them turning on them.

or maybe they improved the zombies, although I can't imagine how.

anyway, they're looking for something that they can create in masses, not just any lucky guy with shonen heart power.