The Wave Inspire is Mizuno's support trainer, and the 21 keeps the approach the brand has used for years: instead of a firm post, a wave plate shaped differently on the inside and outside edges resists the arch collapsing as you load the foot. ENERZY NXT sits under the heel, where you land first.
It suits you if you overpronate enough to want structure but would rather not feel it working. The 12 mm drop is high by current standards and the ride is traditional rather than plush — a steady, familiar trainer for easy days and long runs.
It is not a light shoe at 295 g, and it is not neutral. If your feet are already stable you are carrying support you do not need.