A struggling high schooler on the brink of graduation faces an impossible burden: supporting three younger siblings after his parents' tragic death. Just when survival seems manageable, four of the school's most unapproachable beauties converge at his desk with a shocking declaration—each claiming to carry his child. Reeling from accusations he can't explain, his world shatters further until his grandfather's will reveals an astonishing truth. The inheritance isn't money or property, but CATS—a mysterious system passed through his bloodline for generations, unlocking bizarre and extraordinary tasks that reshape his fate. Now bound by love, responsibility, and supernatural obligation, he must navigate the impossible: satisfying CATS's cryptic demands while building a life with his four wives-to-be and protecting his younger siblings from destitution. Between system rewards and romantic entanglement, he discovers that his "unbelievable life" has only just begun.