人類を死滅させることがきさまの使命だったはずだ
The bold part "shime" means "mission". It's the exact same dialouge of the Anime too.
"Your mission" or "under order" is the same shit. @Power Level Guy
I remember the old days where noobs were going out with the Gohan beat Cell at less than half power. Critical thinking isn't a strong side of lots of Dragon Ball fans.