You wake up in your high school dorm. Umaru-chan, your roommate / stepsister who is also your girlfriend, leaps down from the top bunk and nuzzles you with her cat ears.
“I wuv u, oniichan~” she whispers—but her eye catches the candy on your bedside table. Halfheartedly, you tell her not to eat it, but it’s too late. She gobbles it up with a ^_^ and a “Oishii desu, oniichan (very delicious, big brother!)” You bury your face in your hands; you know what’s coming next.
Her body starts to swell. “W-what’s happening?” Spikes begin to poke out of her abdomen as it grows, slowly at first, and then faster and faster. Her skin, once pale, turns green, while her styled neon-green hair falls out, replaced with waxy fiber. As she expands to fill the entire room, the truth becomes shockingly clear: she is becoming a cactus.
“Uwu, I didn’t want to be this busty~” she whines in your direction. You groan—you don’t have time for this, you’re already late to your whimsical slice-of-life job as a typical high school student. You shake your head and turn to leave, but a call comes through on your Magicka Alarm: “Demon alert! Monster King Amaterasu has broken free from infinity prison!” You sigh—looks like that trip into the girls’ locker room will have to wait.
You punch in the coordinates and roll your eyes—just your luck, he’s in the active volcano on the opposite side of town. As you open the door, you feel a poke from behind. You turn around to see Umaru-chan looking up at you with those big, cactusy eyes. She whispers: “Be safe, senpai~” before blushing and turning away. You smile softly to yourself and push your messy brown bangs out of your eyes. She’s a good kid. But then your expression hardens—this is no time for kids. You’re 15. You draw your weapon and, with a grumble, run there in 3 seconds with your arms behind your back (aerodynamics).
As you approach, Amaterasu summons an awesome giant fire-whip from the Demon Realm, laughing at the puny dagger in your hand. Sighing, you drop it, reach into the volcano, and pull out a lava sword the size of a school bus. You leap at Amaterasu as he swings at you. Flashback: a complicated backstory. The present: you stab Amaterasu with your giant sword. He explodes into a million fox girls in tiny skirts, all of whom try to run away but immediately trip and fall over. The upbeat J-pop outro plays: ♪ ~ Hātobīto de nikutai-teki ni kisushitai… (I would very like to physically kiss you with my heartbeat…) ~ ♫