The meaning of “D.”
“D.” is not short for something, it is a representation of the moon.
Point 1: The D is a suffix to the family name
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In normal Japanese, there are no middle names. In One Piece, this seems to still be the case.
Impact: This means that Luffy’s family name is “Monkey D.”, not “Monkey”. His name in English should be “Luffy Monkey D.”, not “Luffy D. Monkey”.
Point 2: The D is not short for something
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When written in Japanese, the character that would be used to reference this sound in Japanese (ディ, pronounced Dī) is not used. The western character “D.” is used. This is a unique phenomenon in the show, as even characters with western names (Edward Newgate, Marshall Teach) have their names written out in katakana. I argue that this is because the way the character looks is more important than the way the character sounds, which falls into the next point.
Point 3: The Kozuki and Shimotsuki families belong to the Clan of D.
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We have never seen a “D.” in introduced in Wano. However, we have seen a couple of families with resemblant characters. Written as 光月, and 霜月 respectively, these families both contain the character 月 at the end of their names. How did I come upon this? Pure coincidence. In any case, this character, “radical 74” is a Kanji character that can be read as “moon” (tsuki). Why is this related or significant? Because of the origin/evolution of this character:
What did 月 look like thousands of years ago? Starkly similar to the western character “D.”
Could it be that the “月” is a version of the “D” that we are used to?
Random fun facts that can contribute to the theory:
– In chapter 154 where the will of .D is first mentioned, the panel immediately afterwards features the moon prominently.
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– Kozuki Oden and Shimotsuki Yasuie (Ko D. Oden, Shimo D. Yasuie in the western world under this theory) both died with a smile on their faces
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– Blackbeard as a child is depicted crying near a moon (perhaps the moon gives the D.’s the ability to transfer their wills?)
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– The families who overthrew the Ancient Kingdom so far have last names related to the sun, which is thematically often opposed to the moon. Nefertari is a name that refers to an ancient queen of Egypt (they only worshipped Aten, the sun disc). There is a famous work of art by Pablo Picasso entitled “Don Quixote” that prominently features the sun – if Oda is drawing from this, this would also be a sun reference. Could Nika the Sun God be a god of these world nobles?
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Impact: I’m not totally sure what this means. Could this be a reference to their origins? The capital of the kingdom? I can’t really say.
*by yasuke1