The evil idol Majin Gola is awakened by the Dester criminal organization, whose leader Doctor Q seeks to feed it the screams and suffering of children so it will produce rare gemstones from its mouth for him to add to his collection. In response to Majin Gola's reawakening, the guardian deity of the Hydra system finds two brothers, Ken and Ginjiro Mizuno, chosen from birth, and bestows the power to become the Kyodai Ken Byclosser to defend the planet from Dester and Majin Gola's evil ambitions.
Not to be confused with Space Ironmen Kyodain, though the two are similar in concept.
- Bash Brothers: The Byclossers are a quite literal example, being two brothers who fight alongside each other.
- By the Power of Grayskull!: "Cross-Suit!"
- The Chosen One: The Mizuno brothers were each chosen from birth to become the Byclossers because each has a Significant Birth Date (see below).
- Cool Bike: The Byclossers each drive a high-tech motorcycle, which transforms into a cannon for their Finishing Move.
- The Dragon: Sylvia, Doctor Q's assistant and field commander of Dester.
- Friend to All Children: The Byclossers are quick to rescue any children being menaced by Dester.
- Henshin Hero: The Mizuno brothers both shout "Cross-Suit" to transform into the Byclossers.
- Monster of the Week: Each week sees the Byclossers having to contend with a Killer Robot sent by Dester to terrorize children.
- Nebulous Evil Organisation: The Dester organization, a criminal group led by Mad Scientist Doctor Q.
- Nice Hat: The Mooks of Dester each wear a dandy black fedora.
- Overprotective Mother: Katsuko, the mother of the Mizuno brothers, who at one point has bars installed on their window to keep them from sneaking off randomly, though she doesn't know they're the Byclossers.
- Significant Birth Date: Ken and Ginjiro were each born on January 1st, 1965 at 1:01 am and February 2nd, 1968 at 2:02 am, leading them to be chosen by Pegasus to become the Byclossers.
- Wrench Wench: Akemi, Ken and Ginjiro's mutual friend and a gifted repairwoman.