After saving the Pigmon's life during a training session, Zero's actions proved to Leo and Ultraman King that he had matured and revealed to him his true origins as the son of Ultraseven, and when Seven stopped Zero from touching the Plasma Spark, he had saved Zero from following Belial's fallen path. Seven's Eye Slugger then landed at the training ground, Leo realized that Seven was calling for Zero's help against Belial at the Monster Graveyard, and King removed the locks on Zero's Techtor Gear. Redeemed and now freed from his armor, Ultraman Zero took off to the Monster Graveyard to confront Ultraman Belial, with his father's Eye Slugger. However Zero was too late too save his father, and Seven died from the exhaustion and injuries from his battle. Angered by the passing of his father, Zero proceeded to kill the remaining monsters of Belial's army in a mad fury before facing Belial and defeating him, however Belial quickly re-emerged as Belyudra. Zero tapped into the Plasma Spark's power, creating the Zero Twin Sword and decimated Belial with it. In aftermath of the battle, Zero returned the Plasma Spark to its position and reunited with his revived father.