Goro Sakurai is a 24-year-old Japanese pentathlon athlete and Olympic Gold Medalist. A top-tier competitor, he is a champion in Karate, Archery, and Judo, as well as a highly skilled equestrian. He originally turned down Commander Joker's offer to join J.A.K.Q. so he could focus on the upcoming Olympics, but he had a change of heart after being saved by Karen Mizuki.

His bionic enhancements allow him to manipulate Atomic Energy in a wide variety of ways. Using these energies, Sakurai can see through walls and barriers with his X-ray Neutron Scope, move at super-speed by activating his Acceleration Switch, and hear distant sounds at superhuman levels with his Ultra Sound Device.

As Spade Ace, he wields the Spade Arts Power Bow, which fires atomic-charged arrows capable of puncturing dense armor. The bow can also transform into a binding whip. A born leader, Sakurai uses his tactical abilities to exploit enemy weak points, and his atomic powers grant him incredible striking force in close combat. Towards the end of the series, he develops a romantic relationship with Karen.