Core steel on these knives are all VG-10. Mr. Tsukahara makes this same knife with a ZDP-189 core, but they're very hard to get and sell out within hours when they become available. I have a couple of Shun Fujis with SG2 cores (which is also the core on the Shun Reserve series). All are great knives. And yes, Mr. Itou makes a gorgeous set of knives with R-2 cores as well. These are also scarce and sell out quickly.
Shun make great knives, with the bonus they're easy to find in the US. My favorite of their lines is probably the Reserve series. Beautiful, wood handles and custom pins. Very nice ladder damascus pattern on an SG-2 core. Do try to find a Reserve series Shun in person; from my experience, the online pictures don't do this knife much justice.
I'll try to get a few more pics shortly.