If you're looking for manga similar to GATE: Where the JSDF Fought, you might like these titles.
In the Great Orient, lies the continent called Rodenius. One day, an unidentified flying object arrived at Qua-Toyne Principality’s airspace. The unidentified flying object defied the Principality’s common sense. But that unidentified flying object was just a harbinger of something even more shocking. Far to the eastern sea, a group of islands suddenly appeared. The country of the islands called itself: Japan. According to them, their nation had been transported to another world.Now finding themselves separated from their old world and must survive in the new one, how will Japan interact with the native countries of this world? Will they greet her as a friend or as an enemy?
Both these manga feature the JSDF taking on foes in another world!
In GATE - its a gate so worldwide politics are in play [as in bad things will happen if they try to take over and occupy the whole dimension]
In Nihonkoku - Japan is transported, and they have to play more aggressively because they have to import most of their resources from external countries, so they need to play god to set balance.
In Gate a gate to the fantasy world appears in Japan and in Japan Summons, the entire country of Japan is summoned into another world.
Both involve JSDF fightigh in another world, but in Gate it also involve modern Earth's politics in addition to another world's politics.
The ego of modern military power, modern weapons, patriot, morals, human rights, war, politics.
What do you do when your favorite game shuts down? Momonga decided to stay logged in right up until the very end. But when the servers go dark, he finds himself transported into the game world--and he's been transformed into his skeletal avatar from the game, awesome magical powers included! But what if he's the villain of his own story?
If you liked Overlord or Gate: Jieitai Kanochi nite, Kaku Tatakaeri you'd also like the other one because both shows tell the story of a male protagonist from our world going to a fantasy universe with a twist that they're backed up by a military force much stronger than their potential rivals and both take part in the conquest of the fantasy worlds they are in.
Overlord and Gate have also strong focus on politics and diplomacy, dealing with both opponents and allies. The thing I find differing both shows is that Gate has much cuter girls, but they're also there in Overlord too.
When the average Japanese salaryman is suddenly thrown into in a world wracked with warfare and hardship by a supernatural power, they might first think to hide or run away. But not Tanya Degurechaff. A calculating and utilitarian man has been reborn as a child soldier. This young girl will do anything to rise in rank and find a way to live a life of comfort, and woe to any king, country, or god who stands in her way.
In the Great Orient, lies the continent called Rodenius. One day, an unidentified flying object arrived at Qua-Toyne Principality’s airspace. The unidentified flying object defied the Principality’s common sense. But that unidentified flying object was just a harbinger of something even more shocking. Far to the eastern sea, a group of islands suddenly appeared. The country of the islands called itself: Japan. According to them, their nation had been transported to another world. Now finding themselves separated from their old world and must survive in the new one, how will Japan interact with the native countries of this world? Will they greet her as a friend or as an enemy? This is a story of the country called Japan as it was engulfed in the chaotic storm of the world.
When a nuclear holocaust leaves Earth an uninhabitable wasteland, the surviving humans create a new civilization on satellites orbiting the poisoned planet. Eventually, a terrorist attack forces the colonists back to their blighted homeworld, causing a young mother to be separated from her children. For many years Sarah has wandered the land in search of her family, witnessing the worst in humanity as she travels from one chaotic town to the next. No matter what happens, she will not rest until she is finally reunited with her children.
Three days after his sister was no more, he finally gained the will to move. In the aftermath of a goblin raid, a lone boy mourned his village, his family. Five years later, he visited a city on the frontier and became an adventurer. It was five years earlier that the boy who had lost a place to call home was reunited with his childhood friend. Despite being the lowest Porcelain rank, the boy readies himself and then sets off alone for a lair of goblins, marking the beginning of the legend of Goblin Slayer!
Set in the Soviet Union, the mysterious girl named Belka and the quiet boy Shchenok help a Socialist Party member to escape from the secret police. Their aim is to infiltrate into a certain mansion that holds what they seek, but the secret police immediately capture the two. Will they be able to find what they seek and endure the torture of the secret police?
A young priestess has formed her first adventuring party, but almost immediately they find themselves in distress. It's the Goblin Slayer who comes to their rescue--a man who's dedicated his life to the extermination of all goblins, by any means necessary. And when rumors of his feats begin to circulate, there's no telling who might come calling next...
Köinzell is a master swordsman who, along with thirteen other heroes, was sent by the Szaalenden Empire to block an invasion of their enemy Wischtech. Along the way three died, four betrayed the others and seven defeated the traitors and returned as heroes. At least, that's what people believe. In reality the ‘Seven Heroes' were the real traitors, defeating the four true champions after the seven had fled the battle in cowardice. Köinzell has bided his time for twenty years, honing his skills and recovering from the brink of death so that he may avenge his fallen comrades. The time for vengeance has finally come and all who stand in his way shall be dismembered without hesitation, but it won't be easy as everyone believes the lies of the traitors. With all the soldiers in the land and the public against them, Köinzell and his ragtag allies may have to sacrifice everything if they are to prevail against the might of the entire nation.
In the near future, a large portion of humanity is wiped out by a brutal, new virus that hardens the skin while dissolving internal organs. Those who aren’t immune are either severely crippled or allowed to live with cybernetically enhanced bodies. Taking advantage of a world in chaos, a paramilitary force known as the Propater topples the United Nations and seeks world domination. Elia, a young survivor searching for his mother, travels towards the Andes Mountains with an artificially intelligent combat robot. When he encounters a group of anti-Propater freedom fighters, a maelstrom of unique characters unfolds.