A Gate to Desolation

Eighteen years after he returned from that desolate, violent world, Shuzo Mazutani wanted to get on with his life. Off-duty JSDF officer and self-admitted otaku Youji Itami just wanted to buy some doujinshi at an anime convention. Unfortunately for both of them, Shu's dark past invaded Ginza with a vengeance...

A Gate to Desolation is a Crossover Fic for both Gate and the anime Now and Then Here and There by xxSPARTAN119xx. In addition to trying to meld both works into one cohesive whole, the story also makes a point to be consistent with the anime it's serving as a sequel of.

The fic, which has 9 chapters as of 2018, can be found here.

Tropes used in A Gate to Desolation include:

Action Survivor: Shu, this time around. Though he'd rather not have to resort to violence, it increasingly becomes clear that he doesn't want to simply survive either.
Canon Welding: The author makes an effort to mesh the two works into a more or less cohesive whole.
Cassandra Truth: Shu initially kept his story to himself, knowing pretty well that no one would believe what happened to him. Even after the attack on Ginza and Shu being brought in by the JSDF, he suspected that he'd have a hard time persuading others of his account, only to learn that thanks to what happened, the authorities are far more open-minded.
Cool Airship: The "Hammer," Tabul's pride and joy, which he hopes to use against the JSDF. A F4 fighter jet, however, blows it up before he gets a chance to get it airborne.
Crapsack World: The "Special Region," aka the other side of the Gate is still very much this. Even with all the water brought about thanks to Lala-Ru's Heroic Sacrifice, much of the landscape remains a desolate wasteland. While many of the locals, even the supposedly powerful "empire" Tabul's propped up, live harsh lives.
Curb Stomp Battle: Subverted. Similarly in Gate's canon, the attack on Ginza results in a resounding Japanese victory. But as a consequence of the "invaders" having munitions and Schizo-Tech of their own, the ensuing battle is more brutal and destructive, resulting in more casualties.
- It's shown that though the JSDF have a disproportionate advantage over Tabul's soldiers (and could soundly defeat them in open battle), they nonetheless operate as though their enemies are akin to insurgents and terrorists, especially when said foes can still ambush them.
Darker and Edgier: Downplayed, but this is very much in effect by virtue of the source material.
Does This Remind You of Anything?: Many of the actions committed by Tabul's "empire" and the man himself are reminiscent of various insurgent and terrorist groups (particularly in Africa and the Middle East), which is lampshaded in-universe given how the JSDF treat them as though they were. Meanwhile, the rationale given by the Japanese authorities for securing the "Special Region" is made to be more reminiscent of the wars in Iraq.
Doing In the Wizard: It's mentioned that the titular Gate is the result of Tabul and his supporters finding a way to create a portal using a downed airship and Lost Technology into a world ripe for the taking.
Deliberate Values Dissonance: The author makes a very clear point to contrast the brutal, seemingly inhumane norms of the "Tabul Empire" with 21st Century Japanese culture.
The Empire: The "Tabul Empire," a brutal dictatorship forged by Tabul from the remains of Hellywood.
Happy Ending Override: While Now and Then Here and There could be said to have closed on a Bittersweet Ending at best, the fic reveals that it didn't last.
- Over the Time Skip, it turns out that chaos erupted not long after the fall of Hellywood, with Tabul strong-arming what remained of Hamdo's forces as the foundations for his "empire."
- Surprisingly averted, however, with Shu himself. Despite all he had to suffer through while he was in that bleak world, that he's shown to be working in IT and seemingly living a fairly normal life is in itself remarkable.
Knight in Sour Armor: Shuzo Mazutani is heavily implied to be this. He's more cynical, nonchalant and pragmatic than his younger self. But while part of the reason why he considers joining the JSDF forces in the Special Region as an interpreter is the hefty paycheck, he still strongly wants to do what's right and also wishes see if his friends back there are doing alright.
Loophole Abuse: How the JSDF tries to persuade Shu into offering his services without actually recruiting him due to the necessary legislation not yet in effect.
Lost Technology: How the "Tabul Empire" and the "Special Region's" locals at large view the JSDF's arsenal. They even see Earth as being similar to the stories told to them of the "Old Civilization."
Obligatory War Crime Scene: In addition to the brutal antics of Tabul's forces in Ginza, their treatment to captured civilians is also shown. For them however, forcing them into slavery and rape is considered perfectly acceptable.
Meet the New Boss: Tabul has not only taken a level in Jerkass to a greater degree than he already had over the course of the anime, but as the supreme leader of his "empire," he's become little different from Hamdo.
Mythology Gag:
- Youji Itami mentions a number of names from canon!Gate not as fictional anime characters in-universe. Also justified in that the "Special Region" isn't a fantasy dimension.
- Shu's experiences took place in 2000, which was when the last episodes of Now and Then Here and There aired in real life.
Older and Wiser: Shu, who by this point is in his early 30s. The passing of time (as well as having a degree in Computer Science) has allowed him to better understand and speculate on the Crapsack World he endured through as a child to the point of entertaining the notion that said would would have a lot of oil just waiting to be exploited.
Reality Ensues:
- Shu mentioning Sara in his recounting of his experiences causes the authorities to be a tad worried, given how it could prompt American involvement in Japan's claims over the "Special Region."
- It's shown to brutal effect how advanced technology like mechs or hovering vehicles don't automatically give an advantage over a conventional, modern-day military. Especially when said advanced technology is shoddily-maintained or barely functional.
- Although Shu isn't a stranger to guns, he still has to undergo at least some proper firearms training from the JSDF if he intends to offer his services, and not just for formalities' sake. Given how it's likely he hasn't fired a gun in years and the risks involves being in the "Special Region," it'd make sense that he'd familiarize himself with weapons more reliable than the ones he once used.
Schizo-Tech: Tabul's forces have access to among others, hydrogen-powered hovercraft, mechs and dangerous WMDs with the power of a nuke...alongside ramshackle tanks and the sort of weapons one would expect from African warlords or Middle Eastern terrorists. To say nothing of how they have no knowledge of tear gas or aircraft outside of airships.
Shell-Shocked Veteran: Subverted with Shu. He's done rather well enough for himself (at least up until the attack on Ginza), and doesn't have any flashbacks or nightmares. On the other hand, he remains haunted by the deaths he personally witnessed.
Time Skip: The fic starts off nearly two decades after the events of Now and Then Here and There.
Tone Shift: Chapter segments from the perspective of Earth-side characters (especially Itami's) can seem far more upbeat when compared to the utterly bleak tone of those seen from Tabul and his lackeys' side of things.
Twenty Minutes Into the Future/Next Sunday A.D.: Played with.
- The plot takes place in 2019, reflecting the setting of Gate.
- Shu's harrowing experiences, however, are mentioned as having taken place in 2000, which would have been this trope at the time Now and Then Here and There was broadcast.
Year Inside, Hour Outside: Shu reveals to a JSDF officer that he had been in the "Special Region" for about six months, only to come back to Earth and realize that only a few seconds had passed.