Zaion: Anata ga Koko ni Itehoshii

Japanese Title: あなたがここにいてほしい

English Title: Zaion: I Wish You Were Here

Plot
The story of Zaion is set in 2004, four years after the American CDC discovers a meteorite-introduced virus that irreversibly alters the molecular structure of the human body and turns its victims into violent creatures. In an effort to eradicate the infestation that has claimed 3 percent of the human population, the World Health Organization of the United Nations establish a secret internal organization, the Committee of the Universal Resolution of Ecocatastrophe (CURE) in 2002 with several international branches, and creates a unit of soldiers whose bodies have been introduced with nanomachines. These soldiers, wearing Nano Osmolar Armor (NOA), engage the victims in direct combat. They also establish units of unmanned, remote mech units known as Multi-purpose Operative Beings (MOB) to assist the NOA. As the missions begin to take a toll on the NOA's ranks, NOA soldier Yuuji Tamiya (田宮 ユウジ Tamiya Yūji?) (voiced by Joe Odagiri in Japanese and Joey Hood in English) becomes angry at learning that CURE has been working on a secret weapon project, known as UNIT, and not employing it. The Japanese Branch's weapon, UNIT-i, is a girl named Ai (アイ?) (voiced by Yukari Tamura in Japanese and Christa Kimlicko Jones in English) who is able to create a projected being that can destroy the creatures. During the next outbreak, victims of the virus fuse together into a larger creature and overwhelm the soldiers. CURE decides to put Ai's ability to the test, and the projected being destroys the creature.

Yuuji is quarantined after coming in contact with one of the creatures but is released when he recovers from his injuries. However, his blood tests later indicate that the virus has evolved and is attacking the nanomachines in his body. CURE orders for Yuuji's arrest, but he escapes and takes Ai hostage. When his condition worsens during the journey, Ai heals him with her powers. The other NOA soldiers catch up to the two and help them escape, but they are soon found by CURE units. Unwilling to see Yuuji and the others hurt, Ai decides to leave with the CURE soldiers. At the NOA facility, the infected soldiers become victims of the virus as the nanomachines are destroyed. Yuuji is forced to fight them and the CURE units sent to kill them at the same time. Ai finds out that Yuuji is in danger and asks that she be taken to the facility. She realizes her feelings for Yuuji and projects them with her powers to eliminate the virus. A larger outbreak occurs elsewhere in the city, and the virus further evolves to mimic the nanomachines' abilities. Yuuji delays the creatures' advance as Ai creates the projected being once again. She uses all her power to purge the infected area of the virus, but this causes her to collapse in exhaustion. Yuuji runs to her, fearing that she is dead, but she is still alive. Unfortunately, the seemingly defeated virus resists, and Yuuji desperately rushes towards the creatures to fight them. In the end it is revealed that Ai had lost her ability and she and Yuuji had left the organization. In the epilogue it shows Ai and Yuuji spending time together, happy to be free from their duties at last.