An excellent writeup; arigato for your research, Wayne_san. However, I believe you are mistaken in one detail, that being the angle of the vertical posts, the hashira.



You said that a plumb line should fall from the outside edge of the hashira (at the height of the lower horizontal bar, or nuki) to the inside edge of the hashira at ground level; that is, the hashira leans in by an amount equal to its diameter. However, in examining numerous photos of traditional Japanese torii, I find that the outer edge of the hashira (at nuki elevation) almost always lies exactly over the CENTER of its base; that is, it leans in by an amount equal to HALF its diameter. I think you will find that this angle is both more traditional and more visually pleasing, and may even be somewhat easier to construct.



Also, while I agree that when there is only one shimagi (upper horizontal bar) it should be one-third wider than the hashira, few larger torii HAVE only one shimagi; most also have the kasagi "roof" over the shimagi. In those cases, the shimagi's width is actually a bit less than that of the hashira. On the ones where I could tell, it appears to be the same width as the nuki, which would make it one-third SMALLER than the hashira diameter. The kasagi on top is wider than either, and I suspect is at least one-third larger than the hashira (as with the single-shimagi torii you mentioned.) However, on torii that have a kasagi which is actually a pitched roof (like the famous one at Itsukushima shrine near Hiroshima) it looks like the kasagi may be substantially wider than that, perhaps as much as 2-3 hashira diameters.