Towers of Heaven (The Complete Series)

In 2083, six towering structures emerge on Earth, each housing magical monsters and treasures, but posing a deadly threat as they occasionally unleash hordes to attack humanity. Among the mere hundred survivors, a group bravely confronts the towers' final floor, resulting in their demise except for one lone survivor. Rewarded with a wish for their fatal success, he chooses to travel back in time to avert the impending destruction of humanity caused by the towers.