Kyoushoku Soukou Guyver (2005)

Sho Fukamachi's ordinary life ends when an alien device bonds with his body, giving him a powerful living suit of armor. As the Guyver, he becomes the target of Chronos, an organization determined to recover the technology at any cost.

Its transformed human soldiers pursue him and threaten the people closest to him, forcing Sho to master abilities he never asked to possess. The struggle gradually exposes a project far greater than the recovery of one lost weapon, drawing him toward secrets concerning humanity's origins and the future of the world.