Scientist Maya lives a serene life on Planet Katharos until one day, it is come under attack by a cruel race known as the Blasters. The Blasters attack peaceful planets, destroy their resources, and leave them unable to repopulate. Planet Katharos is the latest of their conquests, and they likewise destroy it. However, Maya is able to escape to Earth using an alloy she created called "living metal".
Upon arriving to Earth, she falls in love with the scientist Dr. Hoshi, and the two have a son, Kantaro. Knowing that Earth will inevitably be targeted by the Blasters, Maya forges the "living metal" in her hands using the Earthern volcano into the robot Ganger. However, the rays of the Blaster's attacks eventually take their toll on her and she dies, leaving Dr. Hoshi to continue her mission.
Ten years later, the Blasters commence their Alien Invasion of Earth. Kantaro, now 10 year old, takes it upon himself to protect the planet by fusing with Ganger (yes, he fuses with the robot, Ganger) using his pendant and becomes Astroganger, the all-powerful robot. He repels the Blasters at every turn, and swears to stop them from harming anyone ever again.
In the West, Astroganger is enjoyed ironically, as it's claim to fame is being made by the same team behind Chargeman Ken!, and the two anime have some similarities. Memes of the shoddy animation have been circulated around the internet for ages.
In 2020, Discotek Media revealed that they had licensed it for an English-subbed release.
Has examples of:
- Agent Scully: Dr. Hoshi's boss refuses to believe aliens are real, no matter how much he tries to convince him.
- Aliens Are Bastards: The Blasters kill and de-populate other planets by destroying their greenery and oxygen, for no other reason than they can.
- Alien Invasion: The Blasters do this to several planets, but the two most notable ones in the anime are Katharos, and Earth.
- Attack of the 50-Foot Whatever: Like many other aliens in Super Robot shows of The '70s, this is the Blasters' strategy Once an Episode - and each time, they're beaten back by Kantaro and Ganger.
- Bittersweet Ending: After years of oppression, Kantaro is able to put the Blaster's reign of terror to an end...but it comes at the cost of Ganger sacrificing his life and using the last of his power to create an escape shuttle for him and Rie.
- Blue Is Heroic: When Kantaro and Ganger fuse into Astroganger, he wears a full-blue armored suit with a red helmet.
- Childhood Friend Romance: Kantaro's best friend ever since he was young has been Rie Hayakawa. They eventually both realize that they have feelings for each other.
- Combining Mecha: Astroganger is an unusual case of a human needing to fuse with a robot.
- Culture Equals Costume: In one episode, Astroganger pursues a robot that kidnapped Rie, and he leads him all the way to what appears to be the Middle East (or India). One of the inhabitants is a dark-skinned man wearing a turban as he leads a camel, and once he sees the two Humongous Mechas he screams and flees the scene.
- The Cutie: Rie, with her kindness, big pink bow and friendliness to everyone, is meant to be this.
- Doom Magnet: Because he's the pilot of Astroganger, Kantaro attracts danger when it comes to everyone around him, especially his classmates and Rie.
- Dub Name Change: In the Italian dub, Kantaro Hoshi became Charlie and Rie Hayakawa became Cindy.
- Gratuitous Foreign Language: Maya's planet is called Planet Katharos; "Katharos" (καθαρός) is Greek for "pure".
- Half-Human Hybrid: Kantaro is the result of an Interspecies Romance, as his mother was a Katharosian and his father was an Earthling.
- Human Aliens: The aliens of Planet Katharos, like Kentaro's mother Maya, resemble humans.
- Humongous Mecha: Ganga is 40 metres tall and weighs two tons.
- I Have Your Wife: The Blasters once kidnap Rie and tuck her into a giant Humongous Mecha of their own so that Kantaro can be lured out and attacked.
- Interspecies Romance:
- Maya is a Katharosian who falls in love with an Earthling. They have a half-Katharosian son.
- Rie and Kantaro's relationship can also qualify as this, as he may be half-human, but he's also half-Katharosian.
- Missing Mom: Kantaro's mother died when he was young. When one of the Blasters aliens shapeshifts into a woman who looks similar to her and proclaims that they are his mother's sister, he tears up.
- Named by the Dub: Inverted, Maya has a name in the original Japanese version but the Italian dub refers to her as "La madre di Charlie" (the mother of Charlie).
- Names to Run Away from Really Fast: "Blasters" is an appropriate name for an alien race that want to destroy planets and ruin every planet they've ever touched.
- Once an Episode: The Blasters send out a Humongous Mecha to mess up some cities, Kantaro and Ganger fuse, and the Blasters are left
- Phenotype Stereotype: Since this work is set in Japan, most characters have dark brown or black hair and eyes, while Kantaro has black hair and blue eyes as a nod to his Katharosian heritage.
- Pink Is Feminine: Rie wears a large, pink, polka-dotted bow on the side of her head.
- Primary-Color Champion: Like most mechas of the Super Robot Genre, Astroganger is red and blue, with his armor and chest plate being bright red while the rest of his body is blue.
- Satellite Love Interest: Rie. She's Kantaro's best friend, she's well-liked at school, he has a crush on her...and that's about it.
- Super Robot Genre: Kantaro and Ganger save the Earth with The Power of Friendship (and somehow ignoring the complex intricacies of a human fusing with a robot). The robot is also sentient and breaks the laws of physics on a regular basis. And yes, the theme song is sang by Ichiro Mizuki.
- Token Girl: After Maya (who's dead), the most prominent female character is Rie, Kantaro's childhood best friend and love interest. Some episodes imply that Rie is this at their whole school.
- Tractor Beam: Whenever Ganger needs to transform, it picks up Kantaro this way and pulls him into it's chest.
- War Refugees: Maya arrived on Earth as a refugee from a destroyed planet, and works to save Earth from befalling the same fate.
- World of Technicolor Hair: A one-time character from episode 12 is a little girl with blue-purple hair. Despite this, she's actually not a Blaster alien in disguise.
- Would Hurt a Child: The Blasters don't discriminate when it comes to killing and have no qualms about harming children, but Rie and Kantaro are on top of the list.
