Twenty-Fifth Bam lived in solitude for his entire life until he met Rachel. But now, Rachel has made up her mind to climb the Tower, and she is prepared to leave Bam behind to achieve that goal. After Rachel vanishes behind a curtain of light, Bam chases after her, determined to ascend the Tower in the hope of reuniting with her.
However, the Tower is a perilous realm filled with ancient mysteries, terrifying monsters, and malicious people. Each floor is overseen by an Administrator who subjects the daring challengers to grueling trials that test their every limit.
When he confronts Headon, the Administrator of the first floor, Bam discovers that he is an "Irregular"—someone who was not chosen by the Tower but managed to enter it on his own, an extremely uncommon occurrence within the Tower. Despite this revelation, his course remains clear. Whether it is wealth, power, glory, or even being reunited with Rachel, every desire can be fulfilled at the pinnacle of the Tower.