It's technically not right-to-left. It's columnar top-to-bottom (縦書き), with the columns right-to-left.
In signage you can have one character per column (kind of like one word per row on some English signs), making it look like right-to-left text.
In signage you can have one character per column (kind of like one word per row on some English signs), making it look like right-to-left text.