Just Retired, and the World Sounds an SSS-Rank Alarm

After five years in the military, becoming a commander and being ennobled as a king, he fought alone in a bloody battle against the nine peak Divine Realms at the nation's border. The enemy invaders were almost completely annihilated, but he too was gravely wounded and on the verge of death. Only then did he discover that while he had desperately defended the national border, a catastrophe had befallen his family. His father had been in a car accident and lost an arm. His older sister and brother-in-law had both fallen from a building, while his little niece was suffering from cancer. His mother, who loved him most, had been abducted by human traffickers two days earlier. Her life or death was unknown! In a fit of rage, he removed his commander's robe and relinquished his seal of office. Ignoring every attempt to stop him, he forcibly retired from the military. He swore to rescue his mother at any cost, even if it meant slaughtering ten thousand people. Now that he had returned home, he would kill every enemy who stood against him. And on the very day of his retirement, a top-level global alert rang out!