Damascus pattern on core steel?

Literally, damascus pattern on core steel, not on cladding! I don't have a good camera to catch this pattern, but there is. Can anyone explain it why? I really like this pattern though.

What knife? What core steel?

Mizuno, blue #2. I suspected my eyes at first.

Alloy banding is my guess

James said:

Alloy banding is my guess

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I googled the alloy banding, it certainly looked like it was. Some of the honyaki images had same patterns as well. What causes alloy banding? Is it a good thing? How does it affect on blade in general?

The pattern on core steel is extremely fine like 100 layers. I started seeing this after very deep patina. If there is no patina, I can't see this in naked eyes.

Not sure what knife you are talking about but There are what you call coreless Damascus blades out there. They mix two different steels like the Zanmai aranami (VG2/VG10). I talked to a blade smith about this because I thought it meant the blade would have its hard spots and soft spots but he said the steels kind of split the difference when tempered together. So your paying a whole lot of money for essentially an AUS8 or 6 blade that looks pretty.