The front edge is leading of ship. It means "first" of.... If you live in Japan, you will occasionally see the name of a truck written on it. You will be able to see the reverse order of the letters.
@@Your_Life_is_Good my understanding is for boat only the right side (右舷 / starboard) reversed, the left side (左舷 / port) should be normal. 右舷 ->「丸本日」-> o 左舷 ->「日本丸」-> o 左舷 ->「丸本日」-> x
that’s interesting. the sign of track or something on right side is because of left side road lane in japan. but in the ocean, there may be no such rules.