Board Thread:General Discussion/@comment-27662189-20160617011117/@comment-25942629-20170616230556

Shinoa was born from a Hiragi experiment, the same type of experiment as Mahiru. In the Catastrophe volume 7, fan translators have Shikama Doji comment that Shinoa should be capable of commanding a number of demons. The only thing keeping her weak is her lack of desire, which is why Guren and Mahiru keep wanting to know if she is falling in love with anyone. After all, Mahiru's power grew drastically with her lust.

Mitsuba is a Sangu, one from one of the "royal families" of the Hiragi. I don't know for sure why she was added other than her high ranking. It looks like Guren slapped all of the seraphs into one team with Shinoa and then used Mitsuba to fill in the gap.