Blue Gender started strong... for 15 minutes. It's all down-hill from there. Despite having a ton of tags & genres, it doesn't do any of them well. Quite the opposite, it manages to do every single thing it attempts worse than if it had just neglected to tackle it in the first place. I honestly don't even know where to start with this, but I guess since he was the first thing you're introduced to, let's start with the main character, Yuji. Awoken to a hectic battle, with the power to simply run away in horror, you can immediately empathize with him. He's alone, in the dark, being chased by ominous soldiers and hellish bug monsters, with no clue when or where he is or what's going on. You can understand the angst, the despair, the frustration, the confusion, you can see why he's frightened and jumpy, or to put it simply, this isn't Yuji at his best. However... as the situation relaxes and he gets his bearings, you unfortunately get to see what Yuji is like even when he's feeling better, and it's just as bad. He's sanctimonious, selfish, rash, and his only "good" traits are that he has a basic moral code, and that's it. Unfortunately his more consistent traits, his self-centered impulsiveness means he's always going about doing the right thing in the worst way possible and only the power of hack writing can save his sorry ass. If it weren't for the foot-thick steel plot armor (sometimes literally) around him, he would do more to damage his cause than any mindless bug alien mook or cartoonish evil government asshole. At his best moments, he's tolerable. He's never likable, you will never say "man I can't wait to see Yuji" or "How will Yuji deal with this situation?" An insufferable lead character, and that brings us to his better half (only marginally), Marlene. Marlene is the cool, stony soldier, tough as nails and committed to the mission: except when the author gets horny. Yeah, Marlene is either the stand-in for Yuji, the object of cringeworthy lust or romance-pandering, and basically eye and heart candy, never rising above her stereotype.
That brings me to one of the biggest issues with this show: this "romance" is basically the driving force of everything in the show after the first couple episodes, and it SUCKS. Yuji sucks, Marlene sucks, the two pining for each other sucks, and the amount of ways the plot has to warp and bend to get them apart then bring them back together then take them away from each other then bring them back together over and over again is excruciating. I would suggest you grab a spoon if you wanna watch this with which you may gag yourself. The major conflict of the first quarter of the show is Yuji being torn between Marlene or some nomad fling he meets on the way to the next story beat. It is so ridiculously contrived, and the writing is so sloppy that only that aforementioned double-duty plot armor can keep them from meeting the same fate as the rest of the meat puppets the show throws into harm's way to give the illusion that life in Blue Gender is fleeting. Going by the quick departures for the rest of the cast, with particularly gruesome and unceremonious deaths early on to this end, you would think that life is extremely fragile and death could come at any moment. Yet after the first episode, you can't ever fathom that Yuji or Marlene could ever die. They will always be the last ones standing in the face of wave after wave of endless (and purposeless) bug attacks. The grimdark tone the series wants is entirely undermined by how hasty the writer is to throw Yuji and Marlene into peril and how half-assedly it bails them back out. There's no tension for either of these fuckheads but everyone else in the show is so throwaway and doomed from their entrance that there's nowhere in this to place your concern. The major conflict of this show isn't pragmatism vs idealism in wartime, it's not man vs nature, it's not even man vs man, it's "when will Yuji and Marlene get together?" Gory deaths for the side characters, dismal outcomes for everybody not in the starring roles, frightening stakes for those not graced with plot armor all give the illusion of a serious, mature world and story, but this is a juvenile romance novel for tweens at heart. And to make it clear, I'm not mad that it's a romance. I'm mad that the romance is ass and all other aspects of the show are undermined by it, not that any of them fare much better in terms of quality of the writing.
The show is split into basically two halves, the first half being Yuji and Marlene's meet-cute on Earth and ensuing romantic escapades, and the second half being Yuji and Marlene being kept apart by a comically incompetent evil government in space and tying up (poorly) all of the underdeveloped story threads that aren't the romance. What's going on with the blues? What does the goofy ahh government want Yuji's ass for? Well, you'll get your hand-wave answers but you'd probably be more satisfied if you got your answers from chatgpt. The story is loose and only there to facilitate the cheesy action-adventure-romance, the action is exceedingly dull, similarly perfunctory. Waves of mooks, stormtrooper accuracy and cartoonish bad-guys, the bugs are flip-flopping between unstoppable terminator-ass forces of nature and squishy mindless walking corpses, the action is under-animated and veiled in darkness and often occuring entirely offscreen or on radar screens and there's a lot of standing around gesturing while nothing is happening. Even when it's just combat, no bawdy kissy kissy garbage involved, it's rather dull. Throw in the unwelcome, misplaced, and overemphasized horniness/loneliness and it's just a puke-inducing drag. There's no moral conflicts to chew on, there are no characters or plights to get behind, the only thing keeping you watching will be to find out if it gets on the rails and ever delivers on what the first episode made it seem like it would be, but rest-assured, it doesn't. Nothing but moaning, groaning blah awaits.