The title using the vocabulary "traditional" and the first sentence referring to a switch to the Gregorian calendar in 1873 would lose points on a term paper, for starters.
Then we see this second sentence in the first paragraph:
"Before 1873, however, Japan used a lunar calendar that was completely distinct from the solar calendars first developed by the Ancient Egyptians and the Romans."
That seems a very crafty way of insinuating that the "traditional Japanese calendar" in some way, shape, or, form equates with that of the ancient Egyptians. But according to the National Diet Library the Japanese didn't even have a calendar recognized by the royal authority in Japan until at some point in the 6th century.
Of course, you can blast that manner of thinking with all sorts of fancy phrasing of this or that idea and state that I am off my rocker and so please leave the room, but what I am writing as an analysis could just as easily be supported with that of opposite fancy phrasing and all that.
Then we do not see any reference at all to anything related to the history of the Japanese calendar and the mid-6th century and serious concerns of other elements arise in certain scholarly quarters.