Back in the year 1240 AD, a new type of monsters known as Medallionsters were created by 4 alchemists who created them into life under the will of the king known as Power Rider Tri-O in his plan to help the entire universe.
Though originally mindless, the five Medallionsters gained wills of their own after one Medal in each of the five sets were confiscated.
They are beings that crave, cursed with a void in them that can't be filled without measures.
They lack proper senses, resulting in bleak sensory input (e.g., colors are washed out, taste is nonexistent, sounds are muffled and distorted), as well as the inability to feel deeper emotions such as love. therefore, the Greeed became bent on filling the void left in them by consuming the world, specifically humans, to feel what humans feel.
A Medallionsters consciousness is contained in one particular Core Medal, more specifically the head section. If said Core Medal is destroyed, they will cease to exist entirely, dissipating alongside their Yummies.
Nearly 800 years later, a descendant that goes by the name of Randi, was working with his family in a office building.
One day, as he was walking back home, he was suddenly attacked by a Medallionster.
However, another one show up but decides to help Randi so he can become Power Rider Tri-O
Randi = Power Rider Tri-O
Conrad = Power Rider Birth
Gianna = Power Rider Regen