In a constant speed propeller, why does the RPM drop with a prop pitch increase? When a constant speed propeller changes its pitch from low to high, RPM would decrease.

Why is that the case?

Wouldn't the RPM increase when we increase the blade angle since there's less drag and the blades are more aligned to the relative wind, compared to when it's in a low pitch angle? Also, does higher blade pitch allow us to fly any faster?
The propeller blades indeed have least resistance when aligned with the inflowing airstream, however the inflowing airstream is not the free stream at infinity, but the vector sum of free stream velocity $V$ and rotational velocity of the propeller blade $\omega \cdot r$.



In the picture the local Angle of Attack is indicated as $\alpha$. Increasing blade pitch results in increasing $\alpha$, which means more air accelerated backwards: more thrust delivered, and more torque required.