Ascend the Tower or fall into oblivion.

This is the message that humanity receives when mass amounts of people are suddenly transported to the Tower by a god-like, cruel entity known as the Administrator. Aided by gods from mythology, humanity tries its best to ascend the Tower.

In the end, however, humanity fails.

Kai is a grizzled veteran warrior who, in spite of all his struggles, all his fighting, and all his losses, fails to clear the Tower just like everyone else.

As humanity is wiped out, he is sent back in time.

This time, armed with knowledge and skills he could only dream of before, Kai gets ready to clear the Tower once and for all.