[FairyKing]

This one started just for the pun and then grew from there: Kancho Sentai Mysteryman! (Kancho means spy.) I originally called them Mysteranger, but Sevenlima and Eddy Madison changed my mind. Because their enemies have infiltrated the government, they have to keep their identities secret.

The initial team:
Myster Red! Once a lowly footsoldier of the evil organization SKULL (Secret Knowledge Ultimate Life Labs), he defected from their ranks along with one of their scientists, and together with newfound allies, he began a war to stop SKULL's evil. Serious and focused, he's trying hard to regain his sense of justice and kindness after being a minion of evil, but it's still a work in progress, and he can easily come off as too harsh.

Eventually, he gets exposed to a strange meteor SKULL was using to make their monsters more powerful and more evil, and worries that he'll turn evil himself, but after realizing that power is neither good or evil and how you choose to use it is what matters, he unlocks his super form, Myster Star Red!

Mys Violet! (She'll slap anyone who calls her Pink.) A star martial artist who was kidnapped by SKULL to use in their experiments, she was rescued by Red and the scientist as they escaped from a SKULL lab. Hotheaded and passionate, she'll always jump in to help someone in need, and often finds herself acting as Red's conscience when he thinks too much like a villain.

Myster Blue! A private detective who was investigating Violet's disappearance, he was close to finding the SKULL lab when she, Red and the scientist escaped, and helped them get away and find a safe place to stay. Thoughtful and patient, he prefers not to act until he has a plan, so he usually either has to reign in his teammate's rashness or chase after them, but he takes it in stride.

Two later additions:
Mys Yellow! One of two teenage twins with psychic potential, who SKULL kidnapped to experiment on before the first three rangers rescued her and her brother in a raid on the lab. Shy and quiet, she initially lacks confidence and is scared to fight, but gradually grows more courageous with the help of the other rangers, who she comes to see as her family.

Myster Green! Yellow's twin brother, SKULL successfully transformed him into a monster before he could be rescued, and it was only with his sister's help that the rangers were able to defeat him and restore his human form. Troubled and fierce, even after regaining his humanity he still has a monstrous rage that awakens in battle, but underneath that he really doesn't want to hurt anyone, he just wants to protect his sister.

The true sixth ranger:
Master Shadow! A robot body created by the scientist who led the initial escape from SKULL, with a copy of her own mind. The scientist was injured in the escape which left her too frail to fight herself, but she created the gear and mecha the rangers use, and built the robot so she could still fight beside them in a way. Confident and proud, the scientist and robot share the same goals and ideals, but the robot also wants to prove it's more than just a copy, which sometimes creates conflict between them.

Their mecha are mostly normal-looking vehicles (I know the names aren't very creative, I'm going for a kind of old-school feel):

Red rides the Kancho Bike, a motorcycle.

Violet and Blue don't have personal mecha, but either one can drive the two black-colored team mecha; Kancho Racer, a sports car that combines with the Bike to make Mystery Robo, or later Kancho Hauler, a van that combines with Green's giant monster form to make Cyborg Robo or with Mystery Robo to make Big Mystery Robo. The Racer can fit a second ranger riding along, and the Hauler can fit two extra rangers.

Yellow and Green don't have personal mecha, but Green can take his monster form, a green lizardman-like creature, and grow giant like any other monster. Doing so makes him go berserk until Yellow calms him down, but as part of Cyborg Robo he and the other pilots are in full control. Yellow usually rides along in the Hauler.

Shadow pilots Kancho Chopper, a black helicopter that can transform on its own into Shadow Robo, and combine with Big Mystery Robo to make Sky Mystery Robo, or with Cyborg Robo to make Sky Cyborg Robo.

And finally, after mastering his Star Red form, Red gains the power to summon Kancho UFO, a silver flying saucer that combines with Mystery Robo to make Cosmic Mystery Robo.