Def Märch (Japanese: デスマーチ Death March) is an indie band in Shibuya.
It is formed of:
777, BJ, and Tenho are all Reapers who enter the RG to perform. In the game, it seems Futoshi is most likely ignorant of the fact that his bandmates are leading a double-life, and there is no evidence he is related to the Reapers, as it seems he cannot see Neku or his friends. However, this is different in the anime where Futoshi is a Reaper.
The symbol of Def Märch is their winged microphone, a symbol of their friendship. In Week 2, it is stolen by Sho Minamimoto, who uses it in one of his junk heaps (but leaves his own megaphone in exchange) causing an uproar in the friendship that was later revived. Despite losing their band's symbol, Def Märch planned to use the megaphone instead. After the second day of Week 3, it is unknown whether or not Def Märch still continues without 777, due to his supposed erasure by the Game Master, Mitsuki Konishi.