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 were 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.
A quickie 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 into the next, which is why it's beneficial to not just know your birth DAY, but your birth TIME as well.
Each sign has this thing called a "decanate." 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 decanate, a second, or a third. Check out this handy webpage for an explanation and chart of all the decanates. Long story short, there are 3 signs to each element (Fire, Water, Air, Earth). Each of those 3 signs is grouped together in the decanate chart. An Aries born during the first part of the sign (late March, early April) would have an Aries decanate, while someone born during the middle would have a Leo decanate (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 an decanate if they were born during the first part of the sign, Saggitarrius 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 decanate (Leo is my ascendant, because I was born at 4/14/85 at 1:17pm, when Leo was in my first house... decanates 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 more complete picture, just for you.
Yuugi Mutou - (June 4th) Gemini - Yuugi is flat-out born as a Gemini, the sign of the twins. It's probably not a coincidence that creator Kazuki Takahashi picked this birthday for him, knowing that Yuugi would be "one of two," the host/vessel of the Spirit of the Millennium Puzzle. Yuugi was born during the 2nd decanate of Gemini, meaning his decanate is Libra. People born in the 2nd decanate tend to be thinkers or daydreamers. The 2nd decanate represents the mental side, the aspect of you that is "the Mind." The closer one is to the beginning of the 2nd decanate (as Yuugi is; he's born on the 3rd day of the 2nd decanate, aka the 12th degree), the more they are attuned to new pursuits and adventures. Yuugi's always getting into some sort of new adventure, isn't he?
In general, Geminis are known to be constantly-changing, or enigmatic. They're never what they seem to be! Geminis are also known to be bright, witty, and entertaining -characteristics that Yuugi might not give to himself, but that others might certainly attach to him! His brightness (that is, intelligence, wit) comes from his strategies and his logic, rather than his "book smarts." In the beginning of the manga, Yuugi is humble, modest, shy, and rarely stands up for himself or anyone else. He is also said not to be very smart in school, but he shows his intelligence in a variety of other ways (especially if you consider that the spirit of Yami no Yuugi had to draw on some of Yuugi's intelligence in order to do the things he did, prior to Yuugi or anyone else consciously knowing about him). Geminis don't do too well under stress, and are known to have chest problems (physical, like asthma -perhaps why Yuugi's not too keen on sports?- and emotional, such as heartbreak).
As previously stated, we don't know Yuugi's ascendant, but we can guess based on the personality traits they feature. Some of the possibilities I've considered:
-Taurus (hardworking, steadfast, loyal) approx. 2am-4am
-Cancer (timid, sensitive) approx. 6am-8am
-Leo (warmhearted, generous, courageous) approx. 8am-10am
-Libra (diplomatic, not very argumentative) approx. 12pm-2pm
-Capricorn (prudent, patient) approx. 6pm-8pm
-Pisces (idealistic, dreamer, optimistic) approx. 10pm-12am
And now for some interesting Blood Type information!
Yuugi's blood type is AB.
From Bella Online: Type AB's are the split personalities of the blood groups. They can be both outgoing and shy, confident and timid. While responsible, too much responsibility will cause a problem. They are trustworthy and like to help others.
Sounds a lot like Yuugi, doesn't it?
Actually, the whole concept of matching blood type to personality is a Japanese concept in origin (dating back to the 1930s, when it was assumed that Asian peoples were lower on the evolutionary chain because they tended to have type B blood... studies found that many animals also had B-type blood. But of course, it's possible to have a different type of blood (regardless of race or species!), and so have a different personality!
Now, just like astrology (whether Western or Asian), there's belief about compatibility between blood types-- and we're not talking the scientific "can you be my donor?" kind!
AB is most compatible with AB, B, A and O (in other words, EVERYBODY).
AB characters: Ryou Bakura
B characters: Katsuya Jounouchi, Ryuuji Otogi
A characters: Hiroto Honda, Seto Kaiba
O characters: Anzu Mazaki, Mai Kujaku, Mokuba Kaiba, Sugoroku Mutou
And once again bringing Chinese astrology into the game... People born in the Year of the Monkey are the erratic geniuses of the cycle. Clever, skillful, and flexible, they are remarkably inventive and original and can solve the most difficult problems with ease. There are few fields in which Monkey people wouldn't be successful but they have a disconcerting habit of being too agreeable. They want to do things now, and if they cannot get started immediately, they become discouraged and sometimes leave their projects. Although good at making decisions, they tend to look down on others. Having common sense, Monkey people have a deep desire for knowledge and have excellent memories. Monkey people are strong willed but their anger cools quickly. They are most compatible with the Dragon (1916, 1928, 1940, 1952, 1964, 1976, 1988, 2000) and Rat (1912, 1924, 1936, 1948, 1960, 1972, 1984, 1996).
Of course, one's zodiac sign may not be the one for their particular year, owing to the fact that the Chinese New Year is not January 1st. The Chinese zodiac follows the lunar calendar, which is not strict; the Lunar New Year seems to fall sometime during late February most years. This is why Jounouchi might not fall under the year of the Rooster, even if he is born in 1981; since his birthday is January 25th, he might be a "late bloomer" in the year of the Monkey, like his friends!
One can get even more indepth with this, just like with Western astrology, by using numerology or one's birthday/time to determine a particular element associated with your zodiac sign. There are tons of resources on the web for doing this, so check them out!
I hope you enjoyed this! If you'd like to know more about astrology, blood types, the zodiac, and how it all relates to the Yu-Gi-Oh characters, let me know-- I'd like to do more of these. :)