Ryuzo Taiga is Ken Taiga's grandfather and primary guardian following the death of Ken's parents. An archaeologist dedicated to researching ancient threats, he uncovered critical knowledge about the Dragon Empire, an organization descended from the devil god Jashin Drago that seeks to revive Drago and conquer Earth. Preventing their resurgence formed the foundation of his life's work.

He serves as Ken's mentor, revealing their family's ancestral connection to the Lion Clan, a bloodline destined to wield the power of the divine beast god Agama. This heritage enables Ken to summon and fuse with the symbiotic biomechanical Bio Armor Liger to combat the Dragon Empire.

His expertise proves vital in understanding the conflict's history. He identifies the Myojin Mirror, brought by Ken's relatives Yui and Mai Kamishiro, which reveals the past battle where Agama sealed Drago in another dimension using a large rock as the seal's key. He possesses or knows of a rock necklace given to Ken; this artifact emits a protective blue light capable of countering the Dragon Empire's attempts to break the seal.

During a confrontation between Ken (as Liger) and Dragon Empire general Ryu Dollk, a harmful red light emanates from the seal rock, affecting Ken. Ryuzo intervenes to suppress this energy, successfully protecting Ken but leaving himself vulnerable. Simultaneously, a volcanic eruption triggered by the Dragon Empire engulfs him, resulting in his death while ensuring Ken's safety and the fight's continuation.