As The Gods Will (2014, Takashi Miike)

Finally, Live-action Teen Cartoon Miike gets mixed-up with Bloody Horror Miike. Starts off in a Battle Royale classroom, a fake-looking CG toy playing a game of freeze-or-die with the terrified suit-wearing students, until sole survivor Shun (Sôta Fukushi of Blade of the Immortal) pushes the button on its back. He meets up with the survivors from other classes for the next challenge, basketball vs. a giant cat in the gym, where we meet ruthless brown-haired Amaya (The Great Yokai War star Ryûnosuke Kamiki), then Shun is paired with his ex Takase for a round-robin guessing game, then she’s killed in the next round, in which a truth-obsessed polar bear gets them to turn on each other. Finally a rooftop-sunset game of kick-the-can pits Shun against the transparently evil Amaya. All this is taking place inside a giant alien cube hovering over major cities, which has kidnapped and murdered all the country’s children in order to teach a valuable lesson spoken by a wise old dude at the very end, which I spaced out and didn’t pay attention to.