Salute to the scattered heroes! So, he's a magician. This is a mystery sci-fi episode that a magician sometimes does as a hobby. It may seem a little difficult to understand when it comes to science fiction, but if I had to say it, it would be "a story about a girl who tried to dismantle a biological weapon belonging to an alien that was invading Earth."
The "girlfriend" in this work, Yuura Euclid, is actually a character that the wizard created briefly elsewhere. The story is included in "Evil Fall Fan Book 2B" published by Daken (Evil Fall Research Organization), so if you're interested, please check it out.
So, this work is more of a sequel, or rather, a self-inflicted derivative work. Well, I think it can be enjoyed on its own, and if you're wondering, "Who is Sister Mirein," if you look at the link above, you'll actually find a sample image.
So, on a different note, the idea of "deep-sea ships" became popular as a derivative work of "KanColle." This is a long time ago. Wizards quite like that, or rather, they love the design of deep-sea ships themselves, and they want that type of design to remain a part of the culture of the evil world. That said, ships haven't been followed recently, and there are already a lot of good people doing deep-sea ship adaptations, so maybe we should create some original setting to make it feel like that... No, we did talk about how aliens once eroded us and replaced us as enemies of humanity... So, I thought I'd do Yuura's evil form, which I couldn't do at the time... That's roughly how the content of the work was decided. If you introduce aliens or mysterious invaders in the story, you can easily perform a deep-sea ship-style evil fall. Isn't this going to be trivia?
Well, that's about it, and as a magician, I was able to draw it as a hobby and have fun, but... I hope you enjoy the atmosphere of the parts that are too much of a hobby and difficult to understand. That's what science fiction is all about (explanation)