System: Plunder Demon Lifespan for Martial Arts

Betrayed and dead, Lu Ren transmigrates into a world infested by demons, only to find himself in the body of a universally hated constable, whose decadent life has left him with barely a year to live. Too weak to fight, he's just another morsel for the monsters. But fate, or perhaps karma, grants him a lifeline: a mysterious panel. Its power? Plunder the lifespan of demons he kills, not to extend his own life, but to instantly deduce and elevate his martial arts to god-tier heights. From a pathetic 'Seven Killing Fist' to devastating techniques, every slain demon fuels his unstoppable progression. When the seductive rabbit demoness, who slowly drained his predecessor, demands his final, fatal visit, she expects a dying fool. He plans to offer her a martial arts master... and claim her lifespan as his first true deduction.