How are you with a wheel wrench and a jack?
Jack & support that corner of the car, take the wheel off & have a peek.
Could be a stuck rock. Could be a caliper slider pin has siezed from infrequent use leading to one pad being worn down. Could be the backing plate got dinged and is brushing the back of the rotor under side load. (I had that happen to my car a couple of years ago.)
One way to find out! If you're inclined.
View my fuel log 2015 Micra S manual: 5.0 L/100 km ... 56.5 mpg (Imp) ... 20.0 km/L ... 47.0 mpg (US) ...