Ankokuda, the primary antagonist, initiates the central conflict by journeying from the demon world to the human world and stealing Wataru's conscience, known as his "kind heart" or kokoro. This theft causes Wataru to lose his memories of being the savior and his inherent sense of justice, fundamentally altering his personality and triggering the main narrative. Ankokuda's influence plunges the rainbow over Soukaizan into monochrome, symbolizing the realm's subjugation and the loss of its vibrancy and hope. His reign over Soukaizan is maintained through the Donarukami family, who act as his enforcers and rulers of the corrupted realm. The Donarukami family comprises distinct members: a fire demon king, an ice-cold queen, a sly drag queen named Doran, a mysterious swordsman named Dolk, and an evil child named Dode, collectively enforcing Ankokuda's control. Their characterization deviates from traditional one-dimensional villains, exhibiting complex motivations, personal development arcs, and empathetic traits, though their actions directly support Ankokuda's overarching domination. The stolen "kind heart" functions as both a plot device and a metaphysical concept representing compassion and moral integrity; its absence in Wataru becomes a driving force for the protagonists' quest. Ankokuda's theft carries thematic weight, interpreted as a commentary on societal advancement leading to the erosion of empathy and communal values. The "kind heart" gains narrative significance during battles when it is revealed to be the sole entity impervious to the dimensional-cutting abilities of Sword-King Ryujinmaru, introducing a strategic limitation to the heroes' powers in confrontations against Ankokuda's forces.