"Hareluya II Boy" centers on Hareluya, a high school student with a dual identity. By day, he is an ordinary teenager attending school, but by night, he transforms into a vigilante known as "Hareluya II Boy," using his superhuman strength to fight crime and protect the innocent. His powers stem from his divine heritage, as he is the son of the god Hallelujah and a human mother. This unique lineage grants him immense physical abilities, including enhanced strength, speed, and durability, but also comes with the burden of maintaining balance between his human and divine sides.

The narrative unfolds in a bustling urban setting, where Hareluya navigates the challenges of adolescence while confronting supernatural threats and criminal organizations. His dual life creates tension, as he must keep his identity secret from his classmates and friends, including his love interest, Miki. Miki is unaware of Hareluya's alter ego, and their relationship is complicated by his frequent disappearances and mysterious behavior. Meanwhile, Hareluya's best friend, Ryu, provides comic relief and moral support, often finding himself inadvertently involved in Hareluya's escapades.

The series blends action, comedy, and drama, with episodic storylines that often pit Hareluya against formidable foes, ranging from rogue deities to human criminals. Each encounter tests his abilities and resolve, forcing him to confront the ethical dilemmas of his role as a protector. The narrative also explores themes of identity, responsibility, and the struggle to reconcile conflicting aspects of one's life. As the story progresses, Hareluya's past and the true nature of his divine powers are gradually revealed, adding depth to his character and the overarching plot.

Supporting characters, such as the enigmatic detective Shirogane and the rival vigilante Kurogane, contribute to the series' dynamic, often intersecting with Hareluya's missions and providing additional layers of conflict and camaraderie. The interplay between these characters drives the narrative forward, creating a balance between lighthearted moments and intense action sequences. Overall, "Hareluya II Boy" presents a compelling mix of supernatural intrigue, personal growth, and high-stakes battles, anchored by its charismatic protagonist and diverse cast.