As a way to organize his thoughts, Seiji decided to call the previous timeline with so many people dying the Destruction Timeline. This current timeline he was in would be called the New Timeline.
Voidfire from the Destruction Timeline, or Destruction Voidfire for short, had given Seiji a password. As long as Seiji told this password to New Voidfire, the Voidfire from the New Timeline, it was highly likely that he could convince New Voidfire to change his actions and avoid the Destruction Timeline fate for the city.
However, there was a serious problem with this.
Seiji didn't know what Destruction Voidfire's password meant.
If this password somehow let New Voidfire learn that Seiji possessed the ability to travel back into the past, the consequences would be disastrous.