Kaiju Defense Force

The modern Japanese armed forces are technically not a military: they're the "Self-Defense Force", hence the abbreviation "JSDF" (Japan Self-Defense Force). Also known as the Jieitai (自衛隊), it is split into three branches: Ground, Maritime, and Air (please don't call them the Army, Navy, or Air Force).

According to The Other Wiki, the JSDF's main policies are:
 * Maintaining an exclusively defense-oriented policy.
 * To avoid becoming a major military power that might pose a threat to the world.
 * Refraining from the development of nuclear weapons, and to refuse to allow nuclear weapons inside Japanese territory.
 * Ensuring civilian control.
 * Maintaining security arrangements with the United States.
 * Building up defensive capabilities within moderate limits.

Much of these policies arose from the aftermath of World War Two and Imperial Japan, especially the rampant abuses and societal domination of the Imperial Armed Forces. The Nuclear weapon policy in particular is a reaction to the fact that Japan is the only nation to have ever been attacked with Nuclear Weapons. The JSDF is never officially referred to as a "military", "army", "air force", "navy" or any other similar term.

Contrary to both the title of this article and what you see in anime and Sci Fi movies, Japan doesn't develop advanced weapons technology (primarily relying on the US for weapons) and is not Crazy Prepared for an attack by Godzilla or any other large monster. On the other hand, the Maritime branch is quite large, with lots and lots of destroyers, some AEGIS-capable modifications of the US Arleigh Burke-class. Japan has begun construction of helicopter carriers, but is not allowed to have actual aircraft carriers due to the self-defense laws. Their way around that is to simply designate the carriers as destroyers. Japan's defense budget is the fifth-largest in the world, and it has "breakout capacity"--i.e. it could start building nuclear weapons at a moment's notice and have results within mere months if it wanted to.

Despite the focus on "self-defense", the JSDF has participated in the second Iraq war, and is still in Afghanistan, as the LDP leans more and more to the right and starts developing a tendency for historical revisionism... well, maybe. It is certainly true that the Japanese have been struggling over the use of the SDF in "peacekeeping" roles, as the laws governing "self-defense" never really went into being the third party. What the change of government will do remains to be seen. It should be noted that many of the restrictions on the JSDF are based on interpretation of what constitutes an offensive force or weapon, so in theory it would be easy for the government to change those interpretations.

Japan is currently looking for some new fighter jets. It wants the F-22 ultimately, (good luck with that, as the US has made it clear that nobody gets F-22 exports) but is currently evaluating some of the 4.5 generation fighters (and the F-35), although they're also making their own stealth fighter.

Anime and Manga

 * In Patlabor, the JSDF has the best Humongous Mecha in the country and occasionally cooperate with the Tokyo Metropolitan Police. Captain Fuwa of the JSDF is also a high school friend of police Captain Nagumo, who sometimes calls out favors from her.
 * In Neon Genesis Evangelion, the JSDF frequently deliver The Worf Barrage to the Monster of the Week. They also become Complete Monsters in End of Evangelion, systematically shooting everyone. Even people attempting to surrender. Or--rather, especially--children.
 * Given that the JSSDF has extensive first-hand experience on exactly how futile fighting something that possesses an AT-Field can be, they're quite justified in their strategy of "Kill the pilots". The fact that they fail to kill Shinji and Asuka leads to their deaths.
 * They also gain an extra 'S' in their acronym (becoming the JSSDF), for the "Japanese Strategic Self Defense Force", which might indicate a move to a full military post-Second Impact.
 * It should perhaps be noted that NERV, the organization the main characters work for, is not part of the JSSDF. It is instead a branch of a global organization that is technically UN-affiliated.
 * Space Battleship Yamato, among other series, combines this with Japan Is The Center Of Earth with the Earth Defense Force, with implications that Earth has become as Technically Pacifist as modern Japan.
 * Digimon Tamers has the JSDF attempt to engage hostile digimon and the D-Reaper, but they're largely mere annoyances to the ridiculously powerful monsters.
 * In Zipang, a modern JMSDF Aegis destroyer named the JDS Mirai travels back in time to the Battle of Midway.
 * Anti-Villain Dragon of Earth Kusanagi Shiyuu is a member.
 * 801 T.T.S. Airbats focuses on an all-female stunt flying squadron in the JASDF.
 * In Sentou Yousei Yukikaze, the JSDF is no longer "self-defensive"; not only they maintain an aircraft carrier (named Admiral, numbered 56 in reference to legendary Isoroku Yamamoto), even they are explicitly called as Japanese Navy.
 * The JSDF or their counterparts appear in Gundam twice: in G Gundam, Major Ulube Ishikawa tries to fight off the Devil Gundam with their mobile suits but failed. Sure, Japan now became Neo Japan, but it is possible that the Neo Japanese military is the future SDF.
 * The JSDF is mentioned once in Gundam 00 as being asked by the US military which is the main part of the Union to join the exercise with the Human Reform League and the Advanced European Union. Later in The Movie, one of the Solbraves squadron was a Japanese Brave pilot named Akira Takei, which implies he used to be a member of the JSDF.
 * The primary goal of Ushio Namada, a high school student and protagonist of the manga Satou Kashi no Dangan wa Uchinukenai (A Lollipop or a bullet), is to join the SDF after she graduates, mostly to escape the dull existence of living in a small mountain town.
 * They appear many times in Ghost in the Shell, getting a Crowning Moment of Awesome in the final episode of 2nd Gig.
 * In Gasaraki, the Gowa family is developing a secret weapon system for the JSDF, but there is also realistic debate within the government about the JSDF sending troops to help the U.S. in a Gulf War style conflict. (The Gowa family engineered this, allegedly to help test the mecha, but even that is just a cover-up for their real goal, investigating a strange occurrence where the war is taking place.)
 * In Yomigaeru Sora Rescue Wings, the main character is assigned to a JSDF Air Rescue squadron at Komatsu, where he learns the ins and outs of becoming a SAR pilot.
 * In Un-Go, the JSDF operates a militia-type, paramilitary law enforcement unit called the Public Security Force (or known by its abbreviation, PSC), . Likewise, the JSDF has an anti-riot/guerrilla/insurgency office called the Insurrection Countermeasures Office.
 * Makiro Serada use to be a JGSDF officer before he relocated to Southeast Asia and be a tourist guide there.
 * The Ground Self Defense Force has a minor antagonistic role in one episode of Kamichu! (the real bad guy is.

Film

 * Godzilla and every other monster movie set in (postwar) Japan, obviously.
 * The live-action adaptation of Rescue Wings, which is also set at Komatsu, and featured plenty of cooperation from the JSDF.

Literature

 * The JMSDF and the JASDF heavily in Tom Clancy's Debt Of Honor where they unknowingly serve as The Dragon to China, ironically.
 * In the Axis of Time series of novels by John Birmingham, another JMSDF missile destroyer is among the multinational fleet from 2020 that ends up transported in time back to, you guessed it, the Battle of Midway. Disgusted at not being trusted by the 1940's Americans, and reluctant to possibly kill their own grandparents, most of the crew elects to declare neutrality and become civilians in California, and the ship ends up fighting the Imperial Japanese Navy with a mostly-American crew.
 * It's also the first ship the Midway fleet encounters while the crew are still recovering from the time-travel, initially making for quite an unfortunate misunderstanding between the two fleets.

Live Action TV

 * In the Ultra Series, especially in the Showa ones, the JSDF usually aid the Science Patrol and Ultramsn, only to prove just as useless as in the franchise's sister franchise the Godzilla series

Video Games

 * In one ending of Drakengard,
 * Splinter Cell: Chaos Theory has Japan forming a new branch of the JSDF: the Information Self-Defense Forces.
 * Front Mission 3, set in 2112, features the JSDF rather prominently. They're quickly overshadowed by the Big Bads, but when you face off against them, they're surprisingly competent.
 * It's just the "JDF" by then.
 * Earth Defense Force 2017
 * A Game Mod of Operation Flashpoint Battle over Hokkaido adds the JSDF in both Cold War and modern flavors against the Soviet Union.
 * In Shin Megami Tensei: Devil Survivor, the SDF locks down the entire Tokyo area to prevent demons from leaking out into the rest of the word, and

Webcomics

 * A rather bizarre version (that sets up its own kaiju-related disasters in advance; having an unscheduled kaiju attack is a grievous offense) appears in Megatokyo.
 * Odd for this trope is that they are the police, not the JSDF. (Tokyo Police Department, Cataclysm Division)