Shin Matoba belongs to the Matoba family alongside his father Kazuma and sister Rie. He surfaces as Gai Ogata's adversary in Part II, their clashes highlighted in pivotal promotional imagery. His maneuvers unfold amid mounting crises: Ichijo’s metamorphosis into a Busoma and Kagami’s intricate plots to free her father. During Sayaka Ogata’s emotionally fragile state after profound personal losses, Shin cultivates an interest in her. This development parallels his sister Rie confronting her own dangers. His trajectory converges with Princess Himiko’s calculated initiatives during this period. Shin engages in the overarching struggle between the Shoshidai organization and the Gabi group—both factions pursuing divergent methods to shield humanity from Busoma threats. His involvement intensifies the volatile tensions surrounding Gai’s battle to suppress homicidal urges from the demonic blade Shiryū fused within him.