The thing that comes immediately to mind is Pappy Van Winkel 20 or 23. This bourbon has a very good reputation, and it is certainly something special. The only downside is that the bottle is rather plain. I have never even seen the 23 year old, so I can't comment on that bottle or taste...
Another couple of options might be Blantons, which is awesome and has very nice packaging or Wild Turkey Kentucky Spirit. I've never had the latter, but the bottle looks like something very special.
Another great thing about Kentucky Spirit is that it is not available in Japan, so it will have an extra level of "special" to your Japanese friend. I'd go with the Kentucky Spirit or the Pappy Van Winkel.