Astrology, Blood Types, and Yu-Gi-Oh!


Back in 2006, I began work on a series of articles for the LiveJournal community playthedamncard that examined individual characters’ connections to their astrology sign, blood type, and more.

The series garnered a decent amount of interest, and I added additional features relating to the Chinese Zodiac, Michele Bernhardt’s “Colorstrology” and “Mystical Cards.” Unfortunately, life got in the way of me finishing the series, and I am no longer active on LiveJournal. However, I do still have a strong interest in astrology, tarot, and of course, Yu-Gi-Oh! For that reason, I hope to bring the original articles to a wider, new audience and complete it once and for all. If I find the time, I would also like to apply revisions to the articles so that they all feature the same level of detail.

The series spawned from this LiveJournal post (originally about Mai, but turned into a brief discussion on characters with birthdays on cusps). The “Astrology, Blood Types, and Yu-Gi-Oh!” series of articles is a look at birthdays, blood types, personality, and astrology. Feel free to contribute your own information, as I may be lacking info or simply lacking the time/resources to add it!

Character Ages, Grades, and Birth Years

The year in which the main characters begin their journey is never explicitly stated, but the Yu-Gi-Oh manga first appeared in Japan in 1996. Yuugi, Anzu, Honda, Seto, and Jounouchi (all in the same school, in the same class level), were stated to be 15 years old, but each of them was 16 by the time Battle City rolled around. If you want to use the manga start date as concrete proof, they would have been born in 1980-1981. It’s also important to remember that Japanese high schools work a little differently than many other ones around the world (except maybe those in the Southern Hemisphere):

  • They have 3 grades, 1st year, 2nd year, and 3rd year, equivalent to 10th, 11th, and 12th grades respectively at other high schools.
  • The school year also typically starts in March or April, rather than August or September, so the cut-off for people of a certain age falls at a different time (this explains why Jounouchi would probably be the youngest out of the group, because he was likely born in 1981, while the others were born in 1980. Had he been born in January 1980, he would have been the youngest member of the next class up– too old to be in the same class as Yuugi and the others, short of him flunking and needing to repeat a grade…)
  • Just to inject a bit of Chinese astrology in here, if these years were true, then 1981 would be the year of the Rooster, and 1980 would be the year of the Monkey. The majority of the cast (save Mai, Isis, and a select few other characters of varying or unstated ages) would be born in the year of the Monkey.

I wanted to try and figure out just who is the oldest and the youngest out of the school-going Yu-Gi-Oh cast. In this document (PDF/Adobe Acrobat), it is stated that the cut-off for entry into Japanese primary/elementary school is April 1st. Thus, someone that turns six years of age prior to April 1st of a given year is allowed entry into Japanese primary school, while anyone born AFTER that point is made to wait until the next year. If we stick with the theory of the cast being born in 1980/1981 (speculative; in Vol. 1 of the manga, they’re shown to be in class 1-B, aka 10th grade; by Battle City, they are all age 16 and in class 2-B, aka the 11th grade), then the age roster is as follows:

Italicized names are those whose ages and/or birth dates can be approximated, but are not the same age as Yuugi and Co. Those names belong to characters whose birthdays (month and day) AND ages were explicitly stated, rather than their birthday and grade (as it was for the main cast). Stated ages refer to the character’s age as of their last appearance in the manga. Sun and Chinese zodiac signs are in parentheses.

  • Keith Howard – August 12th, 1969 (Leo/Earth Rooster) – stated age: 26
  • Pegasus J. Crawford – October 8th, 1971 (Libra/Metal Pig) – stated age: 24
  • Mai Kujaku – November 20th, 1972 (Scorpio/Water Rat) – stated age: 24
  • Isis Ishtar – April 5th, 1977 (Aries/Fire Snake) – stated age: 20
  • Ryouta Kajiki – March 1st, 1978 (Pisces/Earth Horse) – stated age: 19
  • Espa Roba – April 1st, 1979 (Aries/Earth Sheep) – stated age: 17
  • Hiroto Honda – April 19th, 1980 (Aries/Metal Monkey)
  • Yuugi Mutou – June 4th, 1980 (Gemini/Metal Monkey)
  • Anzu Mazaki – August 18th, 1980 (Leo/Metal Monkey)
  • Ryou Bakura – September 2nd, 1980 (Virgo/Metal Monkey)
  • Seto Kaiba – October 25th, 1980 (Scorpio/Metal Monkey)
  • Malik Ishtar – December 23rd, 1980 (Capricorn/Metal Monkey) – stated age: 16
  • Katsuya Jounouchi – January 25th, 1981 (Aquarius/Metal Monkey)
  • Ryuuji Otogi – February 28th, 1981 (Pisces/Metal Rooster)
  • Dinosaur Ryuuzaki – December 29th, 1981 (Capricorn/Metal Rooster) – stated age: 15
  • Insector Haga – July 21st, 1982 (Cancer/Water Dog) – stated age: 14

A bit of a trick: if everyone in the main cast (non-italicized) was the same age (15) during Duelist Kingdom, then that means the tournament fell sometime between February 26th and April 17th, 1996. (Japanese law says that you age one year on the day BEFORE your birthday, hence the subtraction of 2 days from Otogi and Honda’s birthdays. I include Otogi’s age and birthday even though he wasn’t involved in Duelist Kingdom, because he’s the same age as them, and was, for a short while, in the same class as Yuugi and Co.)

Furthermore, if Battle City took place starting after April 5, 1997, then the stated ages of Isis (20) and Malik (16) from the Millennium Book would align perfectly with their first appearances.

The thing that screws everything up is the fact that the character guides don’t state at what point in the manga the ages are from; I assume it’s either from each character’s first or last appearance, which is the only way it makes sense to me, given some characters are dead, other characters have moved up a grade since the beginning of the manga, etc. It makes sense for “last appearance” for the main cast members (Yuugi, Jounouchi, Honda, Anzu, Kaiba), and “first appearance” for everyone else.

This is also why technology like cell phones was seen in Battle City (by the early 2000s, it would make some sense to have such technology), but why it doesn’t fit if you assume the birth dates of the characters are as they appear above. Like many manga-ka, Takahashi probably thought of Yu-Gi-Oh taking place in real-time, even if that wasn’t the least bit possible (since when do duels take several months?). It is also unknown what the gap is between the major arcs (Duelist Kingdom to Battle City, Battle City to the Dark TRPG); this also affects people’s possible ages, because it could have been a few months up to nearly a year.

If all the major characters were in the same grade by Battle City, then the tournament had to have taken place on or after April 1st, 1997. (This assumes that Japanese high schools cut-off entrance the same way their primary schools do, and on the same day). It is not known whether the characters are all the same age during Battle City, but that dating helps us figure out the approximate birth dates of the other characters… sort of.

Mokuba Kaiba, while of school-going age, is very difficult to pinpoint, because unlike the others, his age nor grade are never stated in the manga. The only clue we have is the difference between his age and Seto’s, and I’ve seen both 5 years and 6 years. However, he *IS* in primary school (grades 1-6), so that DOES mean he is between 6 and 12 years old, with the most likely ages being 10 (5-year difference from Seto) or 11 (6-year difference). He was born July 7th, which means he started primary school when he was 7, rather than 6.

In the latest edition of the character guidebook (the Millennium Book), Sugoroku Mutou is stated to be 43 years old during the “flashback” chapter that kicks off the final arc of the manga. In the Viz English translation of the manga, the year is listed as 1960, which would mean he was born in 1917. However, he’s stated to be 72 (during the events of the first arc is my assumption), which would imply that Duelist Kingdom somehow took place in 1989?! There’s no way this is accurate, so we either have to accept his age in the guidebook as being accurate or the year in the manga. Alternatively, the original manga used the phrase “the 1960s,” and if we assume 1996 (Yu-Gi-Oh!’s first publication date) – 72 (Sugoroku’s age in the first part of the manga) = 1924 (Sugoroku’s birth year) + 43 (the age Sugoroku was when he found the Millennium Puzzle) = 1967 (the year Sugoroku found the puzzle). That year works, but only if you assume that Sugoroku’s age should be calculated from the manga’s first publication date and that the manga intended to be vague about exactly when Sugoroku found the Puzzle (the 1960s vs. a specific, stated year). Take it as you will.

Grade Approximate Ages
Kindergarten 5-6
1st Grade (Year 1 of Primary/Elementary School in Japan) 6-7
2nd Grade 7-8
3rd Grade 8-9
4th Grade 9-10
5th Grade 10-11
6th Grade (last year of Primary/Elementary School in Japan) 11-12
7th Grade 12-13
8th Grade 13-14
9th Grade (last year of Middle School/Junior High in Japan) 14-15
10th Grade 15-16
11th Grade 16-17
12th Grade (last year of High School in Japan) 17-18

Decans or Decanates

A quick astrology lesson – Not every astrology book or website uses the exact dates and times for when a sign begins or ends. Technically, there are exact times (right down to the second) when the sun moves from one sign to the next, which is why it’s beneficial to not just know your birthday, but your birth time as well.

Each sign has this thing called a “decan.” Depending on what point in your sign you were born (the first degree, the second degree, or the third degree; a total of 30 degrees for each sign), you are a first decan, a second, or a third. Check out this handy web page for an explanation and chart of all the decants. Long story short, there are 3 signs to each element (Fire, Water, Air, Earth). Each of those 3 signs is grouped together in the decan chart. An Aries born during the first part of the sign (late March, early April) would have an Aries decan, while someone born during the middle would have a Leo decan (Leo being the 2nd fire sign in the astrological order), and someone born around April 19th/20th would have Sagittarius (the 3rd fire sign). This repeats for each particular element and each sign; a Leo would have Leo as a decan if they were born during the first part of the sign, Sagittarius if they were born during the second, or Aries if they were born in the third. Make sense? It goes in order. 🙂

I, for example, am an Aries 3rd decanate/24th degree, meaning Sagittarius is my decan (Leo is my ascendant, because I was born at 4/14/85 at 1:17 pm, when Leo was in my first house… decans depend on the week/day you were born in relation to the whole sign; ascendants depend on the specific time you were born on a particular day). The sun had already been in Aries for 2-3 weeks at that point, and since the sun was high in the sky that sunny April afternoon, that affected the rest of my birth chart. The same holds true for the Yu-Gi-Oh characters, even though we don’t know their birth times. We can, however, speculate, which is actually a lot of fun. 🙂

It’s said that when you look up your horoscope, you shouldn’t just read the horoscope for your sun sign, but also for your ascendant. Together, the two of them form a complete picture, just for you.


Throughout my research, I used a number of resources to improve my analysis of the Yu-Gi-Oh! characters and their relationship with their astrological sign, blood type, and so forth. This list represents my most current collection of books and websites:


  • Gordon, R., & Stieglitz, N., eds. (2002). Your birthday sign through time: A chronicle of the forces that shape your destiny. New York, NY: Atria Books.
  • Parker, J., & Parker, D. (2009). Parkers’ astrology (2nd ed.). London, England: Dorling Kindersley, Ltd.
  • Takahashi, K. (2015). Yu-Gi-Oh Characters Guidebook: Millennium Book. Tokyo, Japan: Shūeisha.


The Series

Yuugi Mutou  June 4th, 1980
Seto Kaiba October 25th, 1980
Ryou Bakura September 2nd, 1980
Katsuya Jounouchi/Joey Wheeler  January 25th, 1981
Pegasus J. Crawford/Maximillion Pegasus October 8th, 1971
Ryuuji Otogi/Duke DevlinFebruary 28th, 1981
Malik IshtarDecember 23rd, 1980
Mai Kujaku/Mai ValentineNovember 20th, 1972
Anzu Mazaki/Téa GardnerAugust 18th, 1980
Mokuba KaibaJuly 7, 1985/6
Isis Ishtar/Ishizu IshtarApril 5th, 1977
Hiroto Honda/Tristan TaylorApril 19th, 1980
Insector Haga/Weevil UnderwoodJuly 21st, 1982
Dinosaur Ryuuzaki/Rex RaptorDecember 29th, 1981
Ryouta Kajiki/Mako TsunamiMarch 1st, 1978
Espa RobaApril 1st, 1979
Keith HowardAugust 12th, 1969
Sugoroku Mutou/Solomon Moto October 4, 1924
Pharaoh Atem March 8, 1013 B.C.E.
High Priest Seto August 1, 1016 B.C.E.
Advisor Shimon Muran July 10, 1054 B.C.E.
Priest Mahad August 8, 1019 B.C.E.
Priestess Isis January 10, 1018 B.C.E.
Priest Shada April 28, 1021 B.C.E.
Priest Kalim May 27, 1024 B.C.E.
Priest Aknadin November 26, 1043 B.C.E.
Mana June 26, 1010 B.C.E.
Thief King Bakura June 7, 1013 B.C.E.