X-Blades
37 Achievements
1000
6-8h
Xbox 360
Oops, are you OK?
Kill your first monster
10
How to unlock the Oops, are you OK? achievement in X-Blades - Definitive Guide
Munsie
During the first (tutorial) level, you will encounter a handful of enemies. Defeat any of these enemies (easiest with your sword attack: 
) and the achievement is yours.
SetsunaFSeiei
During the Tutorial, there will be an ambush. Just kill one monster and this is yours.