Sentai are japanese TV series that feature a team of colored heroes who fight evil invaders from outer space who send periodically new monsters to fight them. The monster are always distroyed with a giant robot cutting them in half, and the villain always explode when then die (in fact, everything is subject to explode in this kind of shows)

There is also another genre called Tokusatsu, when the hero is alone and wears a metal armor. Since we are no purists, you will find both in this section, along with other japanese series of this kind.