Someone asked about getting an Astroboy tattoo some time ago in this forum. I also have a cousin with an Astroboy tattoo, she's getting married next month. I wouldn't be surprised if it didn't show up in a few tattoo parlour catalogues. I've occassionally thought about getting a tattoo (my wife says definately not!

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I like to ask people about their tattoos when I see them, and there seems to be two types. One type has a fairly shallow meaning, and is either done on the spur of the moment or when people are young and want to look cool or tough. Often themes of death, weapons, dangerous animals, etc. They tend to regret it later.
The other type is far more interesting, and involves images that have a deep and long-lasting meaning to the person. Things like a family coat-of-arms, a special symbol, something foreign, etc. I think Astroboy is a good choice here, because he so strongly represents Tezuka's message of love, justice, protection, etc.