is the fourteenth single by Bump of Chicken, released on October 24, 2007. The title track is from the album Orbital Period. The single peaked at #2 on the Oricon Weekly Charts, behind , which was released on the same day. The B-side is a remix of "Glass no Blues" from the album Flame Vein.
In September 2024, "Mayday" was used as the soundtrack for an animated short produced by Studio Trigger in honor of the 40th anniversary of the Transformers franchise.