This in lightning fast from blog reader Don, the answer!This hero is "Diamond Eye"! A one season wonder, Diamond Eye fought these beasties in 26 episodes. From japanhero.com Here is the plot line:
An ancient cadre of evil beasts have awaken in modern times and prepare to conquer humankind. With supernatural magic they masquerade as normal humans to infiltrate and destroy civilization. “Shukan Japan” (Weekly Japan) news reporter Rai Koutaro uncovers their plans and attempts to warn the world. Entrusted with the blue diamond “King of Arabia” ring he calls forth the powers of the mystical godlike entity Diamond Eye, the Warrior of Light to battle the beasts and defend humankind.
And more info on our valiant hero:
When Rai Koutaro is sent a package from Switzerland, he finds its contents to contain a magical blue diamond ring. This is the “King of Arabia” ring and is valued at almost 10 Hundred Million Dollars.
In time of great danger, Rai Koutaro is able to summon forth the magical entity of Diamond Eye from within the ring by using the call phrase “Eye Yo!”
Diamond Eye is a mystical being of Light who is a “Spirit of Justice” and a “Warrior of Light”. He is similar in many ways to a djinn or genie in some respects (or even the Tsuburaya hero Ultraman).
Diamond Eye possesses various abilities that can be seen as almost “god like”. He has incredible strength, stamina, and speed far exceeding those of normal humans. He is also incredibly athletic and can perform various complex acrobatic movements.
Diamond Eye is able to pierce through the Ancient Beasts’ mystical disguises using his “Gedou Shoshinrei Hakko Sen” (Inner Soul Illumination Beam).
His sole weapon of choice is his [Diamond] Stick, a sword-like weapon, which he carries constantly in hand. In addition to using it as a stabbing and slashing weapon, from the base of its handle Diamond Eye can fire his “Noble Punch” special attack. His “Noble Punch” attack is a beam ray attack of incredible power that can stun and immobilize his enemies.