Hiseki Senki Stone Buster!(1994)

Tatsuhiko, Jun, and Sayoko are three ordinary friends attending Nagumo High School. But when Tatsuhiko gives Sayoko a birthday charm, they unknowingly awaken the power of a legendary power stone that amplifies the spirit of its wielder. Their ordinary lives are soon shattered as they become entangled in a hidden conflict between the "Stone Busters", fighting a ruthless battle for the future of humanity.

Gifted with the Diamond of Light, Tatsuhiko finds himself at the center of a string of supernatural incidents while powerful enemies close in from every side. With little understanding of the war he's been thrown into, he must uncover the truth behind the Power Stones and the fate they carry. An action-packed fantasy filled with supernatural powers, relentless battles, and deadly secrets!

(Source: Kodansha)