I sort of thought there wouldn’t be enough content for a post when I first noticed this, but times have changed (the following post covers events up to episode 8)
DARLING in the FRANXX is not subtle in a lot of ways. The kids are called parasites (which is what would one could consider children in a vague and general sense), the girls are dubbed pistils while the boys are referred to as stamen, the position they assume while operating the FRANXX are overly suggestive, and so on.
However, FRANXX has been decidedly less overt when it comes to Ikuno’s preferences. Be that as it may, there have been several hints regarding her orientation strewn throughout the series.
For example, Ikuno blushes when she glances at Ichigo’s face while the group leader is directly encouraging the bespectacled girl in episode 4. Admittedly, this could just be a sign of nervousness between friends.
However, she later thinks of Ichigo’s encouragement while trying to sync up with Mitsuru and manages to activate Chlorophytum as a result. In the previous episode, Ikuno was experiencing difficulty in that regard and thus Mitsuru and Ikuno were left behind during the group’s first sortie.
If synchronizing between a pistil and a stamen could be likened to heterosexual coitus, then Ikuno’s conduct could be described as fantasizing about an uninvolved third party while partaking in intimate activities with someone else she doesn’t really care about.
In episode 5, Ikuno bluntly states she isn’t interested in Plantation 26’s stamen after Miku loudly expresses interest in these older and more mature boys. If Ikuno really is into girls, then of course she doesn’t care about these males.
Ikuno acts considerably nicer to Ichigo in episode 7 compared to how she usually treats Mitsuru in aforementioned episode and in earlier episodes, but that could be chalked up to how the two of them are simply not very close.
That sense of distance, however, is made readily apparent once again in episode 8.
While the other boys and girls were relieved and desperate to make amends and apologize for their actions, Mitsuru and Ikuno stand off at the side and just confirm that everything is okay by exchanging glances. They weren’t that affected by the fight since they were never that close to begin with.
Finally, Ikuno mentions that she wouldn’t mind if the boys and the girls never made up. Zero Two immediately sneaks up on Ikuno, licks Ikuno’s neck and slyly proclaims that Ikuno has a secret. Under this context as well as previous hints, it’s hard to think of any other potential secrets aside from Ikuno’s sexual orientation.
Hopefully this can prove to be insightful for the individuals who claim that DARLING in the FRANXX is only promoting heteronormative thematics with little evidence to support such bold statements.