[Sh Ranger]

Delta Gear is weird. Not even I can explain how it works. Chronologically, it's the first Gear developed by Smart Brain and an unfinished prototype since it's not supposed to be compatible with everybody. It's probably not supposed to turn people in to evil Cole MacGrath wannabe junkies either. These side effects don't even come up again after this arc. Delta Gear generates thrice as much Photon Blood as Faiz Gear, it's the most taxing to use and yet it not only doesn't kill humans but actually gives them residual powers. That's weird as hell! What's powering this thing?!

Kusaka was already aware of Delta from his road trip between Episode 18-21 and he seems surprised to see how his friends have suddenly became evil. You know how screwed up they are when Kusaka is repulsed by their behavior. Kusaka thinks Orphenoch and Smart Brain are the worst evil but these guys are way worse. They're worse than Devon when he was high on Fury Cells. However, despite being compatible with everybody, only those with strong will can negate Delta Gear's insanity. The two Ryusei School guys who abducted Mari weren't fit to be Riders.

Delta's Greek letter is, well.... delta. It's not a goroawase pun like the others. It's also a triangle which is symbolic for leadership and supremacy, referencing how it outclasses basic Faiz and Kaixa in raw power. It's like the alpha, except it's delta.