A Scientist Living an Ordinary Life in a Crossover World

(Kaguya-sama: Love Is War + Himouto! Umaru-chan) My name is Daichi Ozora. I'm a scientist determined to explore the universe. But when I was a child, an Ultraman calling himself X showed up beside me. I excitedly asked him: “How can different biological biomes coexist completely in the same line of sight?” Watching him fall into deep thought, I assumed the question was too easy and that he wanted me to figure it out myself. So I swore I would use science to explore the truths of the whole world. Until... “Come be my retainer.” “Do you like staying at home too? And having someone take care of you? Me too!” My life began to change...