As the apex predators on this planet, the one trait that set humans apart from other species was probably intelligence. If other species developed intelligence...
Oppression, resistance, war—this was probably how intelligent lifeforms interacted. If the intelligent creatures created in Sogo Doma's laboratory escaped, this world would probably descend into a war between species, much like Rise of the Planet of the Apes—except the protagonists would be mice instead of apes...
Of course, all of that depended on those mice being able to escape the Doma Residence. So while humane extermination sounded cruel, for the sake of humanity...
"W-Wait, Sogo, doesn't the term 'humane extermination' sound terrifying no matter how you put it? We're still just high school students..."
"Don't underestimate high school students! Besides, why would humane extermination be terrifying? Those mice have no idea how much they envy it..."
"How could any living creature envy being humanely exterminated?!" Utaha Kasumigaoka retorted.
"But that was probably the look of envy on those mice's faces, wasn't it?" Sogo Doma recalled. "At the very least, I thought their faces were full of longing, even though I'd meant to scare them..."
"Huh!?" Utaha Kasumigaoka was dumbfounded once more.
"Utaha, do you want to see it? The entire process of humane extermination..." Having realized they should not keep secrets from each other, Sogo Doma suggested.
"Sogo, no matter how I hear it, this sounds cruel, doesn't it? Wait, why is there an elevator inside the wall of my room?!"
"Just a harmless little mechanism..."
"No, that's way too absurd, isn't it? This house only has two floors, right? An elevator like this..."
"Utaha, don't underestimate the power of the Doma Family!" And don't underestimate me, either... With a solemn expression, Sogo Doma invited her inside.
"B-Basement level eight? Sogo, w-what is this?"
"An