残響 (Zankyou)

Background
Zankyou is an original by 164 featuring GUMI. It is the character theme song of Ouka Tadaomi from the NHN Playart x NND's game app #Compass.

It is featured on the albums "#Compass: Sentou Setsuri Kaiseki System" Original Soundtrack Vol.1 and IVIIV and has entered the Hall of Legend.