The Invisible Challenger

Aliens from the planet Kuuru have kidnapped a number of humans for experimental purposes leading to an impending invasion of the planet Earth. The Terrestial Defense Force is sent to investigate and meets a mysterious wanderer named Dan Moroboshi who helps destroy the invading alien forces. No one knows his true identity, but Moroboshi transforms into Ultraseven, a silver and red dressed superhero from another galaxy committed to protecting the Earth from monsters and alien threats.