Did I get this right: O.G., aye! injected a human egg cell / embryo into a captured gauna ena, and that's how the first hybrid came into being? Seems morally questionable, indeed.
Poor Tanikaze still as a lot to learn about life. It looks like in the underground, nobody ever taught him to knock before entering. Seriously, though, a "boy-walks-in-on-naked-female" gag seems horribly misplaced in this show. Bet this was an eye-rolling moment for a lot of fans.
In good news: It appears (gauna-fied) Hoshijiro is still alive. Yay! I wonder if she'll meet get to Tsumugi at some point.
Speaking of which, when she isn't on the battlefield wreaking havoc, Tsumugi seems just like a little girl that Tanikaze and Izana need to take care of. Especially with her also being voiced by Stephanie Sheh, this conjures up images of Yui in Sword Art Online.