As the OP hasn't returned I wonder if we adequately answered the question? I feel I should point out the a traditional single bevel knife like an yanagi-ba is created in different versions for left-handers and right-handers. Be sure to order the correct one or he'll have a heck of a time using it correctly. A single bevel knife is generally sold semi-sharpened; the knife must be "opened" (the term used to describe the initial bevel creation, polishing of the blade road and creating of the cutting edge). A Tojiro intended for sale in the West may be fully sharped, I honestly couldn't tell you.
If your friend is cutting a lot of boneless, raw fish the yanagi may be a great choice, provided he's comfortable sharpening it. A sujihiki would probably be more user friendly (it's similar to a Western carving/slicing knife). I initially assumed that you knew what you wanted and merely wondered where to get one. Then I reread and noticed that you asked what one was...
If you have any questions beyond this feel free to ask.