Now that's the question we are all here to try to answer!
In filmmaking, video production, and other media, live action refers to cinematography or videography that does not use animation (though sometimes based on an original animated series). As the normal process of making visual media involves live-action, the term itself is usually superfluous, but it makes an important distinction in situations in which one might normally expect animation, as in a Pixar film, a video game, or when the work is adapted from an animated cartoon, such as Scooby-Doo, The Flintstones, 101 Dalmatians films, or The Tick television program. The phrase "live action" also occurs within an animation context to refer to non-animated characters: in a live-action/animated film such as Space Jam, Who Framed Roger Rabbit, Looney Tunes: Back in Action, or Mary Poppins in which humans and cartoons co-exist, "live-action" characters are the "real" actors, such as Bob Hoskins and Julie Andrews, as opposed to the animated "actors", such as Roger Rabbit himself.
As you may have noticed in the wiki definition, the examples are all Hollywood-based movies and actors.
As an intro, please take the survey below [poll] with 5 particular live action adaptations featured - Hana Yori Dango, Death Note, Hana Kimi, Kimi ni Todoke, Nodame Cantabile and you'll be asked which are your personal bias and favorites.
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To put it simply, in the Japanese scene, live action adaptation refers to movies based on manga and anime. Aside from Japan, the US and France belong to the top 3 producers of Live action adaptation based on original manga and comics. I'm not going to go deeper into the differences or similarities of manga and comics, but would like to concentrate on the following:
 An introduction to Japanese live action movies; popular genres of manga and anime; a journey down the live-action lane;
 Statistics on live action films through the years; survey on favorites and list of top 10 live action movies [based on manga and/or anime]
 A look at future productions and mentions of filmmakers, innovators, manga artists (and actors who made waves in the live action scene, including voice acting); and finally answer the question: Do most live action adaptations suck?
In Part 1, we'll take a bird's eye view at the current state of live action affairs!
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The statistics above show how much is the growth of live action movies in Japan - from single digit number in the 1960s to more than 190 live action movies from 2010-present alone, and we're still 4 years before the end of the decade!
Going through the list of live action adaptations from the 1960s until the present:
 Manga live action adaptation begins with an anime version - Cyborg 009;
 The seventies may be considered to be the start of live action movies - Lady Snowblood and the Lone Wolf and Cub (a series of 6 films);
 The eighties is dominated by animation, represented by Akira and Nausicaa of the Valley of the Wind;
 The nineties features Wangan Midnight (a series of 13 movies) based on a Japanese manga series written and illustrated by Michiharu Kusunoki.
 The new decade (the 2000s) features Death Note (movies), 20th Century Boys, Honey and Clover, among others;
 The current decade has already produced the likes of Rurouni Kenshin (trilogy), Parasyte, Attack on Titan, Bakuman, and Himizu, among others.
It also shows how dominant the Japanese are compared to the US and France, considering that Hollywood has produced some of the most popular live action movies in recent years. It's true that in the "west", manga and their live action version are still considered belonging to a niche market vis a vis the Marvel and DC superhero movies, but the global cinematic community is not just Hollywood. To consider manga as belonging to the "other type of comics" is a myopic point of view and a total disregard to the influence and popularity of manga outside Japan and the statistical makeup of its audience.
[ Stats for the movies produced in Japan, the US and France (from 1960s to present) are compiled from various sources on the internet, aggregate total shown including 2016 productions, slated for various future dates. We cannot guarantee the 100% accuracy of the figures. ]
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The above graph shows particular preferences of both Japanese men and women when it comes to the genre of manga. What Japan Thinks originally published an article about Manga preferences of the Japanese taken from a survey conducted in 2012.
Between the 15th and 17th of May 2012, 1,939 members of the goo Research online monitor group completed a private internet-based questionnaire. 60.9% of the sample were female, 6.8% between 15 and 19 years old, 16.5% between 20 and 24 years old, 16.6% between 25 and 29 years old, 16.8% between 30 and 34 years old, 16.5% between 35 and 39 years old, and 17.0% between 40 and 44 years old. [ source ]
I'm not surprised that most prefer gag/comedy, followed by love stories and fantasy and then sports and girls' manga and battles. These preferences are mirrored in today's current crop of dramas - most have the mix of comedy and love story (or perhaps flavors of romance on the side).
While it may take a whole, separate article to just talk about manga genre (and it's anime counterpart/version), suffice to say that the major categories of manga can be classified into:
Kodomo Manga: Comics for little kids
Shōnen Manga: Comics for young teenage boys
Shōjo Manga: Comics for young teenage girls
Seinen Manga: Comics for young adult males
Seijin Manga: Adult comics for males
Redisu (Lady’s) Manga: Comics for young adult females
Dōjinshi Manga: Comic publication that’s written by and for amateurs. Often created for self-promotion
Yonkoma Manga: Four-panel comics (usually published in newspapers)
Gekiga Manga: Comics focusing on serious topics geared toward mature audiences
[ Source: Basic Manga Genres by Kensuke Okabayashi ]
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I would still consider myself new to the manga scene, though I have been watching live action adaptations for more than 8 years already. The thing is, when you become addicted to watching live action adaptations, you start to research on the source, and in this case, manga and anime. In our poll above, aside from the movies, we also asked about the actors who played major characters.
In Part 2, we'll explore Japanese animation, also mentions of famous manga writers and illustrators, plus all about Bakuman!