Crimson Quartet: Pure Elements

Four costumed defenders, Pure Flame, Pure Elizabeth, Black Cute, and Pure Dark, have kept Hyuga City safe from the BB Gang, and they think the job's done. Then the gang's low-level Zako monsters start turning up again, and the team goes out to mop them up without realizing they're walking straight into whatever's actually waiting for them.

The setup is a sentai team getting picked apart one member at a time, dragged from routine monster patrol into something closer to a trap built around them. It doesn't stay a clean-cut hero story for long.

Combat runs on turn-based RPG fights against those Zako and worse, but the real progression is watching four heroines get worn down through corruption, mind control, and the kind of encounters they didn't sign up for, with multiple endings depending on how far each of them falls.