- Voiced by: Yasunori Matsumoto
The main character and a member of the Space Police. He inhabits an android body created by Hiroshi and lives with the Amano family.
- Adorkable: Since he's just new to human culture, he acts like a klutz when it comes to human stuffs. This is mostly averted in case Draias people are around; he talks and acts more seriously in that time.
- Adrenaline Makeover: Once per Episode, Katori pulls the trope when he gears up to fight the villains. He takes off his white lab coat, removes his glasses, and as he gets ready he looks VERY dashing.
- All-Loving Hero: He's exceptionally kind and gentle to nearly any living being he comes across, genuinely tries to see the best in everyone, and adores Earth with all of his heart.
- Badass in Distress: More than once, he's caught in hostage situations where fighting back will only get other people hurt.
- Beware the Nice Ones: A sweet and naive young man who is very good at fighting either in or out of his mecha and can become a fearsome force to be reckoned with to those who he considers enemies. It's quite the treat to see him go from his Nice Guy persona to a Hot-Blooded badass at the flip of a switch.
- Big Brother Mentor: Kenta and Haruka adore him, and Kenta calls him "Katori-niichan" (Big Bro Katori).
- Bunny-Ears Lawyer: An extremely good fighter (whether as Fighbird or as not), a powerful Technopath and a capable leader of the Space Police... and also immensely naive and a bit childlike in "real life", since he's not from Earth and is barely aware of human social conventions.
- The Captain: When on the battlefield, he's a completely focused and VERY efficient leader.
- Clark Kenting: Putting a pair of Purely Aesthetic Glasses and a lab coat on him is seemingly enough to make him unrecognizable. It even gets lampshaded at the end, when Momoko asks him why is he still wearing his coat and glasses and even tells him to take the latter off.
- Elegant Classical Musician: In a way. When Katori plays a lovely song from his home planet in Dr. Amano's ocarina, he adopts a serene attitude that strongly resembles the trope and makes him look more Tall, Dark, and Handsome than Adorkable.
- Expository Hairstyle Change: In his Katori persona, his blue hair is normally combed. When he goes into his Fighbird one, it shifts to more typical Shonen Hair until he has to properly transform.
- Fish out of Water: Katori has zero idea of how human societies work and how people interact, being an alien. A good part of the series' humor relays on him learning about society as a whole under the guide of the Amano family, and often Comically Missing the Point despite their (and Katori's) efforts.
- Friend to All Children: He seems to have an instinctive ability to get along well with babies and kids. Woe betide anyone who threatens children in his surroundings, and double if said kids are Kenta and Haruka.
- Friend to All Living Things: He also tends to interact well with animals. One episode has him happily rescuing a bunch of goats belonging to a shepherd boy and they quite like him too.
- Episode 38 begins with Katori cheerfully playing with Haruka's mascot Champ, just as cherfully interacting with a couple of pigeons and their newborn chicks, and then dedicating himself to help a gigantic gorilla who's been experimented on by Dr. Jango and is being forced to participate in his most recent plans.
- Hot-Blooded: As the protagonist of a Brave Series, that's to be expected. Katori is normally gentle and naive, but when he gets a challenge or is in front of his enemies, he plays the trope straight to the freaking letter.
- Idiot Hero: He comes across as this often, but it's out of being a Fish Out of Water than anything else. He also subverts the trope by being scaringly competent when in missions.
- Incorruptible Pure Pureness: The guy pretty much radiates innocence and kindness.
- Instant Expert: Subverted with his handling of anything technological (he's a Technopath), but played straight when he instantly learns how to surf and plays the ocarina like an expert right after finding one.
- Interspecies Friendship: As an Energy Being in an android body, he has these with several humans: the Amano children, Dr. Amano, Ippei and Goro, Kenta's school friends, little Kaoruko...
- Interspecies Romance: He can also potentially have this with either Yoshiko or Momoko, two women from Earth who develop feelings for him. It's left open ended, though out of both ladies, he's closer to Yoshiko.
- Kindhearted Simpleton: He's got his heart in the right place, but is very simplistic when it comes to life, since he's just created.
- Lethal Chef: His cooking makes Ippei and Goro go pretty much blue in the face. It's understandable: up until then he had never cooked anything so, even when he can eat human food (though it's not his main source of energy/nourishment), he had next to no references about human tastes.
- Episode 40 implies that he cares much more for how nutritive the food is than for its actual taste. Which is why he pretty much pours everything he finds in Akiko's fridge inside the pot containing the stew she's cooking.
- Love You and Everybody: In his and the Space Police's home planet everyone loves one another as soon as they're born, save for truly unredeemable people like Draias. In episode 16 he tells Yoshiko that he loves and admires her and Satsuda; she almost thinks it's a Love Confession and gets a bit flustered, before realizing what he exactly meant.
- Malaproper: Not being a native Japanese, at times Katori tends to mess up with the language. It happens less than one would believe, however.
- Meaningful Name: The Brave First-Born Son (Yutaro / 勇太郎)—Fire Bird (Katori / 火鳥).
- Men Can't Keep House: One would think that Katori's super powers would've been helpful when he tried to assist Kenta's mom with housework. Newsflash: they weren't.
- Naked First Impression: When Fighbird fuses with Hiroshi's android in the first episode, one of his first actions as Katori is to use the silicone foam that Hiroshi keeps around to 'recreate' his human looks, based on a drawing made by Haruka. This doesn't include clothes, so when Kenta and later Hiroshi and Haruka arrive, Katori is completely naked and doesn't seem to acknowledge it as he politely introduces himself to the Amanos and even to Haruka's pet monkey Champ. A very red-faced Haruka tells Kenta to get him some clothes as soon as it's possible.
- Never Gets Drunk: Implied in the Christmas Episode, when the already sloshed Satsuda and Hiroshi hand him a big cup of wine and he simply drinks the contents as if it was water. He's a Type Three: this is all due to his android body.
- Nice Guy: It's hard to find a nicer person than him!
- One of the Kids: Episode 39 has Katori showing up at Kenta and Haruka's school in the typical "observation day" plot. Hilarity Ensues as he ends up enacting the trope to the hilt in the first part of the episode...
- Playing with Fire: Fighbird's more powerful attacks involve a BIG Flaming Sword, and later a just as big fire cannon
- Precision F-Strike: When Ippei and Goro help Katori defuse a Hostage Situation involving Haruka and Kenta early in the story, he screams "now I'm really PISSED OFF!!" before turning the tables.
- Ridiculously Human Robot: He's an android that looks and acts like a human, even if he's a little awkward.
- Savvy Guy, Energetic Girl: Tends to genderflip the trope when he's either with Haruka or Yoshiko.
- Saying Too Much: An early Running Gag has Katori sometimes almost spilling the beans about the Rescue Forces to people he barely knows, so Kenta and sometimes Haruka have to tell him to shut up.
- Ship Tease: With Yoshiko, and to a smaller degree with Momoko.
- Single Woman Seeks Good Man: On one hand, Momoko falls for Fighbird because he rescues her when she needs it. On the other, Yoshiko loves him partially for that but especially for his kindness to people in general.
- Superpower Lottery: He has MANY skills, coming from himself and from the android body built by Hiroshi. Said body gives him Super Speed, Super Strength and the sturdiness to handle both, Technopathy (he's able to use near any machinery and technological appliances by analyzing them on sight) and Super Senses (especially hearing and sight). From his own nature he draws empathy (i.e, he tells Kenta that he trusts Hiroshi completely because he and his companions can sense that his lab is filled with a positive energy, born from the prof's sincere desire to bring world peace), a sort-of capacity to understand near every single living being (especially animals), seeing ghosts (like the spirit of Dr. Amano's late wife Yuri), etc.
- Voiced by: Kōzō Shioya (Ace Baron/Thunder Baron)
- Voiced by: Kazue Ikura
A boy in fourth grade who frequently accompanies Katori on his Space Police missions.
- Voiced by: Rie Iwatsubo
- Voiced by: Ichirō Nagai
Kenta and Haruka's grandfather who serves as their guardian. He is the scientist who created Katori's android body.
- Voiced by: Masako Katsuki
A nurse who often crosses paths with Katori.
- Voiced by: Chie Kojiro
A reporter who frequently gets caught in whatever mess Fighbird has to clean up.