Signal is the gatekeeper at the Kyrie Gate of the Bifrost Bridge, while Signales guards the Yuusari Gate of the Bifrost Bridge. Signal smokes a pipe and uses it to "confirm the identity" of whoever wants to cross the bridge. Signales uses the same method.

Signal's former name was Camus. His other two brothers' names are Sein and Jean. Twelve years earlier, the triplets were Letter Bees. It was revealed in Chapter 38 (episode 14 of Reverse) that the triplets were on the government airship that crashed on the Day of Flicker. Signal was a replacement for Largo Lloyd who couldn't go on that day. The triplets were 3 of the 6 people that survived the crash.