With memories of his father's inexplicable death haunting him, Daichi follows a mysterious rainbow and travels to Tanegashima Island to investigate. Arriving on the island with mixed emotions, Daichi runs into a boy named Teppei who asks why Daichi has returned to this island. Daichi knows he’s returned there to fulfill a promise. Now, with panic alarms sounding and an unruly force known as the Killtgang quickly approaching to attack, Daichi must suit up for the invasion.
Daichi, the son of a former astronaut to gave his life to defend Earth, finds himself in the same situation after returning to the island of his youth.
Daichi learns more about his father's demise, and meets up with familiar childhood friends as his unplanned space mission comes to an end.
The hacker who helped Daichi on his first mission introduces herself as Magical Girl Akari, daughter of the commander. Later, the same Kiltgang who killed Daichi's father launches toward Earth, giving Salty Dog a good opportunity to put Daichi in harm's way.
Teppei is brought in for evaluation after suddenly summoning a Kitlgang to save Daichi. While Hana is being looked at, Daichi and Akari head to town and run into the Kiltgang operators from the moon, now earthborne and ready to start trouble.
Teppei is sent on a secret mission to retrieve Eiji Arashi, who turns out to be his father. With Akari in tow, they attempt to wake him from hypersleep before a group of mercenaries get to him first.
The Kivoto's Plan is the last resort for Earth: jettison it's most important humans and let the Kiltgang devour the rest left behind in order to make them move on. With both opposing factions considering such a dangerous solution, the danger looms ever closer.
What Kiltgang activity rising, Daichi once again takes the helm of the Earth Engine to protect the planet. Teppei seems reluctant to help when things get tricky, afraid of losing himself to the Kitlgang.
Pitz has pinpointed the net appearance of a Machine Goodfellow, and the newly appointed Midsummer's Knights head to the location to investigate.
Akari is kidnapped by Amarock to hack into the low orbit impactors and bring them down. Little does Amarock know, the tables are about to be turned and he has a critical choice to make.
Lin has been awakened. Daichi works to stop her but it is too late, Liebam has been summoned. Can Teppei stop her in her tracks using his Nebula Engine?
One of six designer children, Setsuna's sole purpose is to keep Marimura young forever. Will she ever escape Marimura's lab?
Daichi is sent to an underground fighting tournament to find the last of the designer children named Baku.
Baku's wishes may be stronger than bullets when he saves his love Kumiko from sure death.
Daichi learns about the feelings Hana has kept secret from him while on his day off.
While Hana and Setsuna flee Amara and Moco. A trap is set up to kidnap the CEO of Macbeth Enterprises.
With the backing of Macbeth Enterprises, the Planetary Gears feel empowered in their new position.
The Midsummer's Knights worthiness is under scrutiny by an investigator from Salty Dog. Moco and Zin try to attack Earth and they commandeer the interceptors that Salty Dog Dispatched. Can Daichi and Teppei stop Moco and Zin and prove their skill?
Marooned in Australia after a botched re-entry into Earth, Daichi, and Teppei work to protect Hana from being captured by enemy forces.
Salty Dog will stop at nothing to capture Hana and sends his unmanned Impacter to intercept Daichi and the hijacked transport ship.
Two of the three top players in the Intercept Faction come to Tenkaido to oversee the start of Operation Summer. They are unimpressed by the young Midsummer's Knights and doubt entrusting a mission that will save the human race to children like them.
Hirosue, who announces he is not operating on behalf of Salty Dog, has taken Hana captive and set bombs all over Tenkaido. Unfortunately for both parties however, another even bigger threat arrived on the same shuttle as he did.
Commence Operation Summer. The flight path of the Blume is interrupted when they are met with the resistance of the Ark Faction and their weapon the Garm Engine. Will the Blume make it to Uranus and the fortress carrier Oberon in time?
Daichi gets a strange feeling while he is at a school conference with his uncle. Little does he know, he is being coaxed by the Planetary Gears to remain in a dream world. Will memories of his past and his friends bring him to his senses?
The Midsummer's Knights reach the Auberon and have the Planetary Gears in their sights. The Planetary Gears recognize the fortitude of the Midsummer's Knights and decide to offer them a chance to join them. Puck however, reveals how he really feels.
Puck intends to become the supreme leader of the all. He takes control of Blume and possesses Hana. The Planetary Gears learn that in order to stop puck they must sacrifice themselves. Daichi fights harder than ever to save Hana and end Puck.