I will also address that that I have a 47” chest with maybe 18.5”-19” shoulder width. These Japanese makers get crazy with the shoulders and somehow think if someone has a 44”-46” chest then their shoulders must be 21”. Even some of the tallest most broad shouldered guys on this board are probably closer to 19” in shoulder width.
Hm? If anything, Japanese designs go the opposite direction with shoulders, making them unusually narrow compared to the other measurements, not wide.
Grading patterns with 18 or so as the shoulder size for 40 as a baseline is pretty universal. It will scale up but this doesn’t mean the jacket will be boxy.
I have jackets with shoulders that are dead on, a half inch wider than mine, 1.5” wider than mine, and all of them fit. Certain materials or construction techniques will also increase the shoulder measurement.