Hi Pawel and Göran,
That makes sense as KG55 (or KG(J)55)! I just checked
http://www.ww2.dk/air/kampf/kg55.htm: KG55 was equiped with Me 109 G in the second half of 44 and in 45. I haven't seen a photo of a Me 109 before with this emblem on it. Very interesting.
Thanks
Roger