Hmmm, this type of horn and the shape of the handle (and is that a large horn 'washer' between the hilt and guard?) reminds me of the huge Golok I've got below, which took me to Java and then to Sumatra. The faceted star reminded me of something I'd seen about Sumatra in WW2 and the Japanese, which took me to this:
http://www.hubert-herald.nl/IndoSumSel.htm
"In 1942 the Gouvernement Sumatra, created in 1938 was occupied by Japanese Forces and placed under the jurisdiction of the 25th Army. This army had a five-pointed faceted star as its emblem."
Just some thoughts.
Beautiful sword BTW! Congratulations.