Wait, I Taught You to Be a Security Guard, So Why Are You Guarding the Nation’s Borders?

[System, high-martial arts, no female lead, ensemble cast, character growth, traits] Kong Xuan transmigrates to another world invaded by myriad races and awakens an “Unparalleled Profession System.” As long as he trains students, he can claim lifespan bonuses and martial arts techniques. Just as Kong Xuan thinks everything is settled and he can lie flat in peace, he draws a career path and gets a security guard. Looking at his eldest disciple, who has the trait of a future Martial Emperor, Kong Xuan speaks earnestly. “A security guard doesn't just watch an ordinary gate. He watches over the gates of our homes and cities, and guards the very gates of our nation!” His second disciple, who has the trait of a Mind-Thought Overlord, gets lockpicking. Kong Xuan says with a straight face, “Lockpicking isn't limited to physical locks. Bottlenecks, genes, even the boundary between life and death can all be locks!” Until the myriad races return and the land lies in ruins! A towering man stands before the nation's gates, killing the invading enemy with a single punch and shaking the world! “My teacher once said I was a security guard. Then I am the security guard of the human race, protecting its peace!” A peerlessly beautiful woman stirs a thought, and the myriad races are wiped out! The dead return to life! “My teacher once said I was a locksmith. Then I shall unlock the locks for humanity. Even life and death are locks!”