The Ten Days of Darkness is an event that occured in the Medabots anime.
This event happened 8 years before the start of the Medabots anime, during a World Robattle Championships match. Hikaru Agata (A.K.A Henry) was Robattling with a Medabot named Metabee. Back then, Hikaru's Metabee consisted of the current Arcbeetle's Medal in a Metabee body.
Hikaru's Metabee eventually Robattled so fiercely that its Rare Medal energy caused the whole world's Medabots to riot, having their memories of being rulers of the earth and warmongers awakened by the energy. They rioted for 10 days before Hikaru made the painful decision of ending his Metabee's functions to stop the transmission of the energy, thus calming the world's Medabots down.
This event had a major impact across the world, directly affecting the lives of many characters in the anime.
|This event led to the birth of Henry's two alter-egos, the Phantom Renegade and Space Medafighter X. the Phantom Renegade's purpose is to serve as Dr. Aki's covert (and illegal) agent, stealing Rare Medals and handing them to Dr. Aki to prevent anybody from holding a Rare Medal and possibly triggering the event again. Space Medafighter X's purpose is to allow Henry to continue robottle in the open, with him being a wanted man because of the incident.|
Henry's Metabee had its Medal destroyed to finally end the Ten Days of Darkeness. Its Medal seems to have been partially repaired (albeit without its old memories with Henry) and became Arcbeetle.