Why does Piccolo bleed two colours?

Question

In the above pictures, his blood is of two colours. Before Dragon Ball Z, his blood was red but later on in the series it became purple.

What is the reason behind this?

Answer 1

This has been an item of discussion between Dragon Ball fans for a long time. Most of the information I've come across concludes that this is simply an animation consistency failure.

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From Dragon Ball Neoseeker Wiki:

The vast majority of the manga was produce in black and white, with a few chapters being colored minimally. There were also an even smaller number of chapters in full color.

Since Dragon Ball was originally black and white, the animation studios likely did not know that Piccolo's blood was supposed to be purple until much later.

In fact, this Reddit comment points out that it happens with Frieza's blood too, discoloring it from blue to red.

While some arguments have been made wondering if this could be censorship, the blood changes were in both international and Japanese versions of the show. There are several cases of censorship that involve the Dragon Ball Z anime but I do not believe this is one of them.

However, there was some censorship on some international releases of Dragon Ball Z involving Piccolo's blood. These changes turned Piccolo's blood green.

A fact that points towards this color change being a blunder is that Piccolo's blood is recolored to purple in the first episode of Dragon Ball Kai, during the recap of the 23rd Tenkaichi Budoukai. This screenshot is from Piccolo's reaction when Goku headbutts him. Interestingly enough, this scene also receives some censorship in international releases, recoloring the blood yet again to white.

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As an aside, it is likely that not even Akira Toriyama really knew what color Piccolo's blood was supposed to be. In an interview with Toriyama, he states that he was originally unsure that Piccolo would even be an alien; he originally just created Piccolo to be demon-like.

Q: Speaking of Piccolo, did you think from the beginning of his background as a Namekian alien?

A: Of course, I didn’t think that at all (laughs). The Saiyans were like that as well. When I thought up Goku’s tail and the Ōzaru, I didn’t think Goku was an alien or anything. Piccolo either. Because I thought that up when God came out. Mostly afterwards, I thought it through so that it would be consistent. For example, there’s the chair that Planet Namek’s Eldest sat in. That was mostly the same as the chair that Piccolo Daimaō had sat in when he first appeared. It was just missing the skulls.