How about making our sentai a vigilant type of thingy~ and our villain would be like cops?
so here's what I've got: (I don't know if it's bad or not..)
The milky way was one of many galaxy across the universe but it's the center of all sins. An organization called Galaxy Enforcer soon taken notice that the peace of this universe are off due to the sin activity in the milky way especially on earth. Without holding back, the prime leader of Galaxy Enforcer, Galacticus brought a thousand fleet of soldiers to Earth, the source of sins. With his army he stumbled across the Novasphere, another organization which bring the balance to the galaxy. The Novasphere sensing danger on the balance, they went to stop the army but their attempt are at vein. With a sad defeat over Galacticus, Novasphere made devices which were later sent to the earth hoping that these bracelet could hold against Galactus or more even kill him. The devices later be sent by a higher-ups of the Navasphere whilst to give them to a specific DNA bonded (which means there's no outer being that has successful to bonded with the device) with the devices.
