Complex sentence: Somehow arriving at their intended goal just on time, there appears in front of them a beautiful girl holding a bouquet of roses, who hits Mitsuo across the face with them and hands the flowers over to him.
Split into simpler sentences: Somehow arriving at their intended goal just on time, there appeared in front of the two a beautiful girl holding a bouquet of roses. The girl then whacked Mitsuo across the face with the bouquet and handed the flowers over to him.