Board Thread:Off Topic/@comment-1478058-20150314002647/@comment-1478058-20150610145349

Ok found the full plot.

Eiji is Dark Drive and uses a currupt Belt-san.

http://kamenrider.wikia.com/wiki/Kamen_Rider_Dark_Drive

Shin is then forced to use the Trideron Key and the Mach Driver to become Super Dead Heat.