The 999 reached its final destination, the planet Promethium. Once on the surface, Tetsuro and Maetel were escorted by Mirai, who brought them to the sanitarium where Tetsuro had up to 24 hours to contemplate his decision on adopting a mechanical body. Maetel warned Tetsuro to think wisely before leaving him with Mirai to meet her father, whose consciousness was encased in a pendant. In the sanitarium, Tetsuro realized that the life of a cyborg was empty and disappointing, and decided not to take his machine body. He also witnessed a cyborg committing suicide and, in his last moments, warned Tetsuro of Maetel's intentions, and that she was the daughter of the Queen of Promethium. In a confrontation between Tetsuro and Maetel, Mirai explained that Maetel was to bring courageous young boys like him to help construct an eternal mechanized empire.
Tetsuro arrive enfin à la destination finale, Promethium. Cependant, il ne parvient toujours pas à choisir s'il veut devenir un cyborg ou non. On lui accorde vingt-quatre heures pour prendre sa décision. Pendant ce temps, Tetsuro discute avec un cyborg qui est fatigué de la vie éternelle et tente de se suicider. Cet homme révèle à Tetsuro la véritable identité de Maetel en tant que fille de Promethium. Ensuite, son guide, Mirai, informe Tetsuro qu'il a été choisi pour être un soldat d'avant-garde de l'Empire Mécanisé. Tetsuro confronte Maetel...
