Shun Kazami co-invented the Bakugan battling rules with Dan Kuso, becoming a top-ranked competitor before a hiatus prompted by personal circumstances. His early journey was deeply affected by his mother's illness and death, with cultural variations in the narrative surrounding her passing. Trained in ninja techniques by his grandfather, Shun typically operates as a lone strategist yet deeply values his teammates, acknowledging their critical importance across multiple conflicts. In Bakugan: Mechtanium Surge, Shun is approximately 18-19 years old. His appearance evolves: during the first arc, he sports layered attire featuring light and dark green accents, tan pants, light brown boots, a dark green choker, and longer hair. For the second arc, his outfit shifts to a green or black jacket over a green shirt, white pants, and black shoes. Initially ranked fourth in Bakugan Interspace due to reduced battling while focusing on ninja training, his formidable skills remain. He grows suspicious of Dan Kuso's erratic behavior and concealed struggles with Drago's unstable powers, correctly deducing Dan's actions endanger the team. Shun's primary Bakugan partner changes. In Arc 1, he battles with Ventus Taylean. Arc 2 introduces Ventus Jaakor as his main partner, alongside Darkus Skytruss and Darkus Orbeum, obtained through whistling. This marks his first tactical use of dual attributes (Ventus and Darkus), expanding beyond his traditional Ventus specialization. These three Bakugan combine into Magmafury, a Ventus/Darkus Baku Sky Raider. Jaakor generates the Mechtogan Ventus Thorak, and Shun collaborates with Marucho Marukura to deploy the Aquos/Ventus Duomechtra Mechtogan combination. When Dan temporarily relinquishes leadership amid his struggles, Shun assumes command of the Battle Brawlers, emphasizing traditional battling integrity over Bakugan Interspace's newer mechanics. He confronts antagonists like Anubias and Sellon, demonstrating strategic prowess. During the final conflict against Wiseman and Mechtavius Destroyer, Shun joins in deploying the Current of Time to prevent the annihilation of Bakugan City and its inhabitants, cementing his role in preserving their reality.