Jackknife Dragon, true name Findar the 100th, hails from Dragon World as a green Armordragon. He serves as the dedicated buddy monster to Tasuku Ryuenji within the Buddy Police organization, where he holds a notable reputation among its monster members. Despite possessing the capability to shrink, he consistently prefers remaining at full size during daily activities. Through their partnership, he grants Tasuku the ability to fly.

His bond with Tasuku extends beyond duty, rooted in deep familial ties and unwavering trust. This connection is reflected in his declarations: "I will protect him. It's not a duty, he is family," and affirmations like "If we are together, it will be possible to proceed down any path." Their synergy is central to his character, emphasizing loyalty and mutual reliance.

During a significant evolution after training with Armordeity Dynamis, he underwent cybernetic enhancements, transitioning from Dragon World to Star Dragon World. This transformation marked a new phase in his capabilities and role. Throughout conflicts, including Tasuku's temporary corruption and alignment with the Disaster Group alongside Demios Sword Dragon, Jackknife Dragon remained a stabilizing force. Following Tasuku's return to his original ideals, their partnership was fully restored, reinforcing their enduring connection.

In his later years, as Tasuku advanced to the position of commissioner within the Buddy Police, Jackknife Dragon continued to serve alongside him.