@markderrick The problem could be the font(s) used by Freemarker just don't have a glyph for the Japanese characters, so they aren't able to be rendered. NetSuite now offers Google's Noto Fonts for the advanced pdf templates which cover a much wider range of unicode characters than most fonts. You can put the following in the head element:

<link name="NotoSans" type="font" subtype="truetype" src="${nsfont.NotoSans_Regular}" src-bold="${nsfont.NotoSans_Bold}" src-italic="${nsfont.NotoSans_Italic}" src-bolditalic="${nsfont.NotoSans_BoldItalic}" bytes="2" />
<link name="NotoSansCJKjp" type="font" subtype="opentype" src="${nsfont.NotoSansCJKjp_Regular}" src-bold="${nsfont.NotoSansCJKjp_Bold}" bytes="2" />

Then, in your CSS styles:

font-family: NotoSans, NotoSansCJKjp, sans-serif;

Obviously, the downside is that you are changing fonts, and it will change both the look and format of your templates. You could use a mix of other fonts, along with the NotoSansCJKjp, though, or alternatively upload a preferred font with Japanese character support to the filing cabinet, and reference that font instead. I think SuiteAnswers has an article for how to do that.