The Saint's Magic Power is Omnipotent (Light Novel) Vol. 1

Could workaholic office lady Sei be a legendary Saint? Not according to the crown prince of another world who summoned her and quickly declared a different girl was the real Saint! That suits Sei just fine--she would much rather spend her days quietly helping people with her unbelievably powerful magic. But how long can Sei live her ideal life of leisure before her true nature is revealed?