Genkō yōshi (原稿用紙), also romanized at genkoyoshi, is a type of Japanese paper used for writing. It is printed with squares. There are typically 200 or 400 squares on each sheet. Each square designed to accommodate a single Japanese character or punctuation mark.
There are lots of PDFs available online but sometimes the squares are too big or too small, the page size is wrong, etc.
I found some good ones from Ed Halley at http://halley.cc/nihon/patterns.html These genkouyoushi PDFs gives a nice faint space for furigana. But, again. we will always want to have the posibility to adapt it to our own needs. So these Asymptote http://asymptote.sourceforge.net/ scripts with several parameters allow the customization of the page size, the size of the boxes, margins, line thickness and color, etc.
##Rules of use
While genkō yōshi can be used for horizontal writing, it is most commonly used for vertical writing, which is read from right to left. The first page is therefore the right hand side of the sheet. The title is placed on the first line, usually leaving two or three leading blank spaces. The author's name is placed on line 2, with an empty square or two below and an empty square between the given and family names. The first sentence begins on line 3 or 4.
In Japanese, each paragraph, including the first one, is usually indented by a square. However, when writing quoted text such as direct speech, the opening quotation mark (﹁ or ﹃ in vertical writing) is placed in the first square of the line.
Like printed vertical Japanese, full stops, commas, and small kana are placed in the top right corner of their own square All punctuation marks, other marks (such as parentheses), and small kana usually occupy their own square, unless this would place them at the top of a new line, in which case they share the last square of the previous line with the character in that square. (This is the kinsoku shori rule.) A full stop followed directly by closing quotation mark are written in one square.[1] A blank square is left after non-Japanese punctuation marks (such as exclamation points and question marks). Ellipses and dashes use two squares.
Furigana are written to the right of the relevant character, in small print.
Words, phrases, and sentences in Western characters (such as Roman letters) except acronyms like USA and NATO are often, but not always, written vertically by turning the page a quarter turn counterclockwise, so that when the page is viewed normally they are sideways. Each square can accommodate two Western characters.
Then assuming you have already installed asymptote, the following command will generate a PDF file that you can print or share:
asy -f pdf traditional.asy
Note that en this example we use the traditional.asy file, this may differ in your case.