Series: Choushinsei Flashman aka: Chou Shin Sei Flashman
On one fateful day, five children from Earth were kidnapped and sent to the far reaches of outer space. Twenty years later...
Chōshinsei Flashman (Supernova Flashman) is the tenth Super Sentai show, airing from 1986 to 1987.In 1966, the Reconstructive Experiment Empire Mess authorized the abduction of five kids for the purposes of their experiments. The benevolent beings from the Flash Galaxy saved the kids, and took each of them to a different planet of their solar system. Twenty years later, with the abilities they gained from the training on these planets, the now-grown kids return to Earth to fight the Mess as the Flashmen. There's just one problem: since they've been away from Earth for so long, the planet's atmosphere has become deadly to them, so they can only stay for a year; otherwise, they die of the Anti-Flash Phenomenon.
Home Base: The Round Base, a large building that can go into space.
Humongous Mecha: The first Sentai team to have a second giant robot. The first robot was the usual combining mech, while second was of the transforming kind.
Combining Mecha: Tank Command (Red) + Jet Delta (Green and Yellow) + Jet Seeker (Blue and Pink) = Flash King
Transforming Mecha: The Flash Titan truck, which transforms into the support robot Titan Boy, which can then combine with its trailer to form the Great Titan.
Law of Chromatic Superiority: Nastily subverted once the Anti-Flash Phenomenom causes the Flashmen to temporarily lose their powers; Jin is the first to go.
Make My Monster Grow: Kuragen's reason for living. Interestingly, it's a strange variety of Liquid Assets. It's like there's only so much "big" to go around, so ginormous scary-looking Kragen appears, makes the monster big... and then shrinks down to the size of a gerbil and has to scurry away from the battlefield as fast as his little tentacles can carry him. It's hilarious.
Monster of the Week: The Jūsenshi or Beast Warriors, creatures created by Lee Keflen's genetic synthesizer from the genes of Earth's animals (the final series of monsters were created by combining the genes of Ra Deus himself with those of his underlings).
Mooks: The insectoid Zolors, complete with acid webbing.
Bizarre Alien Biology: Their years on the Flash planets have altered the Flashmen's genetic makeup, giving them superpowers but making it impossible for them to stay on Earth for more than a year.
Bittersweet Ending: Sara finds her real family, she and the other Flashmen destroy the bad guys, but they have to leave the Earth for the sake of their lives.
It was never stated that they couldn't return after recovering for a year or two, though. Thus, making it not as quite as bad. However, it is still the one of the only two sentai so far to not end on an overly happy note. The other being Timeranger, which is probably worse.
Everything Trying to Kill You: Anti-Flash Phenomenon. To wit: You touch fellow humans? You get electrocuted. You touch flowers? The flowers gas you. You try to drink? The water chokes you. You stand around in the open? The sun burns you.