yes the power is from the mask, it sorta augment one's physical abilities be it speed/strength, but the wearer will have to bear the drawbacks (the mask sorta controling you to perform tasks you dont want to do) and also the physical setback (considering human limits, the mask is basically pushing oneself over that limit and it will damage the body, most notably seen at last ep, where he just moved in super speed and after that he sorta "died")

also, initially, the wearer was the priest, however he died later on, and hayato continued the mask's legacy, only for a short while until he was "brought back from the dead" from that secret organization.