My System Makes Me the 999,999th King Arthur

One moment, Lin Sizhai was enjoying a bath. The next, he's naked in a fantasy world, bewildered, until a random golden sword slams into him, declaring him the 999,999th King Arthur! Now saddled with a castle and a bizarre Knight Summoning System, his first roll yields a beautiful swordswoman. Just as he's getting used to his absurd new life, a global broadcast from a mischievous Merlin drops a bombshell: ancient barriers are down, and continent-spanning hordes of foreign invaders, from magic dragons to mountain-sized seals, are swarming. With other King Arthurs fleeing en masse, Lin Sizhai's coastal castle is now ground zero. Will this accidental king fight for glory, or flee like the rest, leaving the continent to burn?