Wow...it looks like you're not getting a whole lot of help here.
I'm a graphic designer operating a design company here in Japan.
To get you to where you're trying to be, I recommend using any "Mincho" typeface. That's the serifed variant in Japanese typography. If you have some Japanese fonts installed on your computer, they should have the name "Mincho" in the title of the font. If the font name is Japanese, look for these characters: 明朝 or みんちょう (hopefully those characters render correctly on this forum).
If you need help choosing a font and don't know what all the weird names mean, I wrote a blog specifically to enable people like you to get where you need. Here's the blog:
Hopefully this'll help you do what you need to do. I do recommend you have a native speaker or experienced designer help you with this if possible. If your eye is good enough, you could always try out a few different typefaces in paragraph form and print them out. You'll never get that gray tone that you're looking for because of the nature of the characters but it'll help you with line-spacing and choosing a font with decent kerning. Factory-installed typefaces should be ok. Another bonus having an experienced designer is they can tell you how to separate, punctuate and format the font in the correct style. With no Japanese experience, that would be nearly impossible, unfortunately.
P.S. If the book you're translating is a novel, that's generally written vertically from right to left. Best of luck!