How to rotate a gameObject towards a hit point along Z axis?

my camera is on Z axis.. all of my objects are on the x-y pane.

so, i have a game object with an arrow sprite pointing up. I want to have that arrow head pointing towards the hit point.

I have a function that is called upon Raycasthit is known:

      Quaternion toHitRotation = Quanternion.FromToRotation(hit.point, Vector3.forward) * this.transform.rotation;
      this.transform.rotation = toHItRotation;

however, it doesn't work. I check the gameobject, instead of having x & y being zero, now, there are values in x & y, and things get weird. I tried to "normalized" by adding:

      this.transform.rotation = this.transform.rotation * Quanternion.Euler(0,0,90);

and still doesn't work.

what did I do wrong?