How are character's birthdays decided?

[Alfieri]

I always wondered how an anime/manga character's birthday is decided?

Does the mangaka give the character a birthday based on the day the character was conceptualized or completed?
Or does the mangaka research horoscopes and picks a birthday based on the character's and astrology sign's personality traits?

 

[Oryx]

Probably it depends on the individual deciding the birthdays. I know Red's birthday in the manga was the day the first volume came out, and others make a big deal of listing star signs, so probably a little bit of both.

It would also be a nice way to sneak a friend in too, putting their birthday as a character's.

 

[Judge Mandolore Shepard]

I think that when anime and manga creators come up with characters, they tend to make the birthday be on signifincant dates. For example, in Hitalia, all of the characters birthdays are each country's Independence Day since each character is a personified country.

 

[Alfieri]

I think that when anime and manga creators come up with characters, they tend to make the birthday be on signifincant dates. For example, in Hitalia, all of the characters birthdays are each country's Independence Day since each character is a personified country.

That makes sense. But then what about the likes of Naruto, Natsu or Luffy's birthdays?

 

[donavannj]

That makes sense. But then what about the likes of Naruto, Natsu or Luffy's birthdays?

I haven't delved too deep into those 3 series, but it could just be a completely arbitrary date that the author thinks suits the character. It's probably happened this way about as often as the author using some pattern to determine them or the birth dates of people they know as character birthdays.

 

[Satoshi Ookami]

Random dates, cool dates, dob of friends of mangakka, birthdays of seiyuus...
Pretty much random.

 

[Akiba]

Now explain how they select the characters' blood types.

 

[Satoshi Ookami]

Now explain how they select the characters' blood types.

They throw a four side dice.
Anything else?

 

[Yuoaman]

There's a superstition in Japan and other East Asian countries that your blood type determines aspects of your personality. It's basically the same reason that people list a character's star sign in their biography's.