@tag98, indeed! Should be quite interesting. Somehow ironclad just has a special place in my heart.
I found the whole process quite good. Gaku obviously took effort to adress my wishes. His replies were short and concise, sometimes a tad minimalistic perhaps. But I got answers to all my questions. For example, I asked them to make the knife with a straight back instead of the curve their Kiritsuke normally has, and he was very accommodating.
At one point, I didn't receive an answer for two weeks and then sent him a kind reminder. That was answered promptly. He also highlighted several times that waiting times are long. And since I had trouble with their Japanese shop system and the translator didn't work, he immediately agreed on taking my order via e-mail. Like I wrote, I got quite a list of special wishes, and the only thing that made a difference from the stock price was the 15k Yen for the ebony wa handle. None of the other wishes did raise the cost. Of course, the AS 240 knives are very expensive to begin with lol. So all in all, it was very good.
My experience with custom orders is limited. So far I had contact to TF (4 knives), Zakharov (2 knives) and now Isamitsu. All of them were very forthcoming and helpful, beging non-native speakers (like me). Ironically, the only maker I didn't go through with an order because communication was too difficult and I wasn't sure we were on the same page was a maker from Britain.
One thing that might have been interesting is what the fine finish for 7700Y will give you. He wrote "hand finished cutting edge", which is not something I would have needed to spend money on. But for a nice FnF with a well-done Kasumi, I'd have paid this in an instant. But this uncertainty is on me, since I didn't ask.