Tesshin Okada runs the Sagami model shop, a central hub for Mini 4WD enthusiasts. His technical skill is evident in his creation of the Shining Scorpion, the first Mini 4WD car with a ZMC body—a lightweight, ultra-durable composite material. Dr. Tsuchiya praised this innovation as groundbreaking, though he remarked that Tesshin viewed the design as "a decade too soon" for widespread competitive racing.

Tesshin built two identical Shining Scorpion units. He entrusted one to his assistant, Da San Yuan; decades later, Da San Yuan’s grandson Huang raced it with Team Guang Xie (Light Scorpion) in the World Grand Prix (WGP). The second unit went to Takeshi Sugiyama—later known as Mini 4WD Fighter—ten years before the series’ main events. Fighter kept this car and instantly identified it when another unit appeared online.

In the "Mini 4WD Shining Scorpion Let's & Go!" video game, Tesshin appears with Dr. Tsuchiya. Both provide the player with the Shining Scorpion during a visit to the Sagami shop, cementing his mentorship and support for new racers.

Tesshin Okada features as a supporting character in the WGP anime series. He does not appear in later seasons (MAX), the sequel manga "Return Racers!", or related spin-offs.