The main protagonist of NEO and an athletic 17-year old student in his 3rd year of high school. After finding the Sigzarl and piloting it to protect his hometown, he is drawn into events transpiring both in his own world and another, all while looking out for his younger brother, Amane.
He pilots the Sigzarl, a knight-esque machine originating from an alternate world, which gains more power as Kakeru gains the various Armed Phantoma. Eventually it evolves into the Shigzarius.
- Big Brother Instinct: Since their parents aren't home very often, he is extra protective of Amane.
- Heroic BSoD: After the situation with his brother takes a turn for the worst, he falls into one, forcing Sharl to slap him out of it.
- Instant Runes: Most of his machines' attacks create these.
- Leitmotif: The Sigzarl has "Spiritual Transmission" as its default theme, and "Extreme Degree" for its final attack.
- Upon upgrading to the Sigzarius, his default theme becomes "Sword of Justice", which becomes "Ultimate Energy" for his 2 strongest attacks.
- Magic Knight: His machines' switch between using the sword Armed Phantoma to magical bomb-esque lasers.
- Ordinary High-School Student: Just a regular kid in his last year of high school, taking care of his Ordinary Elementary School Brother...and then a weird ship and robot show up out of nowhere just when their town gets attacked by monsters.
Kakeru's younger brother and a 10-year old boy in his 4th year of elementary school. When their town gets attacked, he ends up bound to a mysterious ship, more-or-less forcing his brother to pilot the robot that came with it to find him a way out. Little does he know this would be the least of his problems.
He "commands" the ship "Ionia" except during his time possessed by Larva, where he pilots the Alsignos, the brother machine to the Shigzarl.
- Cain and Abel: During his time possessed by Larva, he is the Cain to Kakeru's Abel.
- Dude Looks Like a Lady: He gets some flack for his feminine looks.
- Evil Counterpart: Alsignos is this to Shigzarl.
- Instant Runes: The Alsignos creates these for its attacks.
- Leitmotif: "Mysterious Power". When possessed by Larva, he has "Majestic Enigma" and "Rush of Shudder" as his themes.
A 19-year old girl from another world helping her older brother with his archeological research, and a former member of Ernst, until she left due to disagreeing with their methods. She ends up getting transported to Earth in search of the Armed Phantoma, where she encounters Kakeru.
She pilots the witch-esque machine Merveille. During Amane's period of possession, she takes over commanding the Ionia.
- Brainwashed and Crazy: Forcing the brothers to fight and snap her out of it.
- Get a Hold of Yourself, Man!: Does this to Kakeru to get him out over his Heroic BSoD.
- Hair Decorations: Two diamond-shaped decorations on each side of her hair.
- In-Series Nickname: She's more often referred to as "Sharl". Kakeru also calls her "Donut Girl", but she very much objects to that one.
- Leitmotif: "Magical Spectrum", which changes to "Brilliant Valkyrie" for her final attack.
- Noodle Incident: See Rivalis's entry.
- Ship Tease: With Kakeru, with some of their interactions borderlining on Belligerent Sexual Tension. After Larva is defeated, she ends up staying on Earth, partially because it "probably won't be boring being around him.".
- Trademark Favorite Food: After collapsing from hunger upon landing on Earth, Kakeru gives her some donuts. They quickly become her favorite, to the point that's what he knows he by (hence the above nickname).
A penguin-like being from the other world. He starts off as an antagonistic bandit and general annoyance.
He pilots the Penpada, which somewhat resembles him.
- Ace Custom: His Penpada draws its basis from the Ernst mooks' machines.
- Everything's Better with Penguins: Him and his mech.
- HeelFace Turn: Starts off antagonizing the brothers until he's saved by Amane.
- I Owe You My Life: Towards Amane.
- Leitmotif: "Flying Column of Bonehead", which also has an "SPmix" for his final attack.
A high-ranking member of the other-worldly organization Ernst.
He pilots the Debajno and its upgrade, the Debajno β. He also briefly pilots the Alsignos before it gets hijacked by a possessed Amane.
- Ace Custom: His machines are customized from the machines used by the lower-ranking Ernst memebers.
- HeelFace Turn: He joins forces with our heroes right before they try to snap Amane out of his possession.
- Leitmotif: "Strike Head On", later switching to "Rock Me βmix" for his final attack.
- Multicolored Hair: It manages to be red and blond.
- Noodle Incident: Apparently something happened between him and Sharl involving a rejection, but there isn't a whole lot of elaboration.
- The Rival: It's right there in his name. Specifically who he is a rival to is somewhat up for debate.
- Undying Loyalty: Towards Chaos.
Leader of the the other-worldly organization Ernst.
She pilots the Signix, based off the data from the Alsignos.