"Otaku" is a Japanese word literally meaning "you." Its actual meaning is an ardent follower; a fan. There are many types of otakus in Japan. Food otakus, airplane otakus, weapon otakus, and of course, anime otakus. In the American anime culture, though, otaku is used to describe anime fans exclusively.
So how otaku are you? Here's a pop quiz. What do these three characters have in common with each other?
Linna (Bubblegum Crisis), Unipuma (Dominion), Rei Hino (Sailor Moon)
Too hard? How about these:
Alielle (El-Hazard), Ryo-ohki (Tenchi Muyo!), Yoriko (You're Under Arrest!)
Still too hard, then try this last set:
Ranma-chan (Ranma ½), Nuku Nuku (Nuku Nuku), Ai-chan (Video Girl Ai), Momiji (Blueseed), Rei (Evangelion), Tira Misu (Bakuretsu Hunter), PenPen (Evangelion)
There are many parts of being an otaku. At the base is loving anime. But after that, there are offshoots. One of them is knowing your seiyuu. Seiyuu (pronounced "say you") is Japanese for voice actors and actresses. And as you should have guessed by now, each group of characters are linked by having the same voice actress. The seiyuu for the first group is Michie Tomizawa, the second, Etsuko Kozakura, and the third, Megumi Hayashibara.
Unlike the American animation industry, in which the voices of characters are largely anonymous, seiyuu in Japan are very well-known. One aspect that seiyuu otaku will notice is who is doing the voices for the characters in an anime. Some of the bigger names in the industry include Kikuko Inoue (Kasumi, Rune Venus, Belldandy), Kotono Mitsuishi (Usagi, Misato), Ai Orikasa (Ryoko), and Yumi Takada (Aeka). Currently, the biggest seiyuu in the industry is undoubtedly Megumi Hayashibara, who seems to be in just about every other popular anime one can think of.
One thing you may have noticed is that all of the seiyuu mentioned above are female. This strange ratio is because most male seiyuu are of an older generation. It is very common, in fact, for female seiyuu to play the roles of young male characters like Shinji from Evangelion, whose seiyuu is Megumi Ogata. Among the better-known male seiyuu are Kappei Yamaguchi (Ranma-kun, Tombo, Sosuke), Kouichi Yamadera (Ryouga, Dosetsu), Masami Kikuchi (Tenchi, Keiichi), and Yasuo Yamada (Lupin III).
In addition to providing the voices for anime, seiyuu also frequently sing theme and image songs for the anime they're in. One example of this is Bakuretsu Hunter, which is being shown tonight. Other examples of this can be seen in You're Under Arrest!, Tenchi Muyo!, El-Hazard, and of course, Bubblegum Crisis. While having seiyuu sing is not a particularly new occurrence (think back to Minmay from Macross), the popularity of their singing is. Many seiyuu now have albums under their own names unrelated to any specific anime. A number of seiyuu also host radio and TV talk shows. The cast for an anime will also do live "events"; stage shows to promote an anime. Just try picturing the cast of Teenage Mutant Ninja Turtles doing an "event," and you'll see the difference in the American and Japanese industries.
The joy in being a seiyuu otaku is esoteric. To begin with, many seiyuu are actually fairly interesting personalities. But after that, there is fun in the trivia; for instance, noticing that two characters that sound similar have the same seiyuu or even noticing that two characters that sound completely different have the same seiyuu. One also begins associating certain seiyuu to certain roles. For example, the soft-spoken, a little clueless, and slightly older female role is a common domain of Kikuko Inoue. Young male characters are frequently voiced by Kappei Yamaguchi, who is well-known for these types of parts. The loud, tomboyish girl is frequently attributed to Megumi Hayashibara. It's because of this association that it was interesting to learn that Hayashibara was the voice of Rei from Evangelion, a very quiet character.
The interest in seiyuu comes from the richness of anime as an artform. Much as people recognize the styles of artists and directors, so do people recognize the seiyuu. It's true that this knowledge won't help you graduate or make you fabulously wealthy. However, knowing your seiyuu adds a dimension to anime that takes it beyond the simple act of watching to a more complete enjoyment of the artform.
Seiyuu otaku scale