In PlayerSpriteKasua.h you need to re-declare whatever methods you're going to override/implement (without the "=0" to say that those methods are not abstract anymore). So you need to write it like follows:

class PlayerSpriteKasua : public PlayerSpriteBase
{
public:
    virtual void think();
    virtual void render(long long ScreenX, long long ScreenY);
    virtual int getHealth();
};

...or did you omit that to keep your post shorter?