i thought it was a common isekai story novel

Well, a common isekai novel usually has a few typical elements. For example, the protagonist is often transported from our normal world to a fantasy world, either by being reincarnated or some kind of magical accident. There's often a system in place that gives the protagonist special abilities or quests to complete. Also, there's usually a power - up journey where the main character gets stronger over time.

Common isekai stories typically follow a set formula. There's the sudden transfer to a different world, often accompanied by a truck-kun moment (where the character is hit by a truck and wakes up in another world). Then, there's the discovery of new powers or skills, making friends or allies, and usually a grand quest to save the new world or achieve something great.

One reason could be the marketing. Maybe it didn't get as much promotion as other popular isekai novels. Without proper marketing, it's hard for a book to reach a wide audience, even if it has good content.

A big trope is the 'fish out of water' situation. The character from the real world has to adapt to the strange rules and customs of the isekai world. Also, there's the 'chosen one' trope. The protagonist is somehow destined to save the isekai world or fulfill a great prophecy. And let's not forget the 'gaining levels' or 'power progression' trope, where the character gets stronger as they complete tasks or defeat enemies.

Well, it could be the character development. In some isekai novels, characters are just one - dimensional. But if this one has complex, evolving characters, that's a big plus. Also, the world - building might be more intricate than the common isekai. Instead of the typical medieval - like setting, it could have a blend of different eras or cultures.

One element could be the setting. For example, instead of the typical fantasy world, it could be set in a post - apocalyptic isekai world where the protagonist has to deal with both the new world's magic and the remnants of a destroyed civilization. Another aspect could be the protagonist's unique ability. Most isekai protagonists have common powers like magic or super strength, but if the protagonist has an ability that's not often seen, like the power to control time in a very limited and strange way, it would make the story less common. Also, the way the story deals with the concept of 'returning' can be different. In a common isekai, the protagonist may not think about returning at all, but if the whole plot revolves around the protagonist's struggle between staying in the new world and finding a way back to the old one, it would stand out.

The 'OP (overpowered) protagonist' is a big trope in isekai. If this story doesn't have that and the protagonist struggles a lot more than expected, it's a subversion. In many isekai, the protagonist quickly adapts to the new world. But if in this story, the protagonist has a really hard time adapting, like constantly getting into cultural misunderstandings or being unable to use the magic system effectively for a long time, it's different. And the 'defeat the big bad evil' plot is common. If this story focuses more on the smaller, personal battles and character growth rather than a grand, world - saving mission, it's subverting the trope.

One unique aspect could be the way the protagonist is transported. Instead of the usual death - and - reincarnation or magic portal, it could be something really different like being pulled into a painting or a song. Another thing could be the world - building. If it has a really strange and unique world, not just the typical fantasy stuff, like a world made of living crystals or where emotions are physical entities.

A common theme is self - discovery. When a character thinks they are the main character, they often go through a process of learning more about themselves. For example, they might realize their flaws or hidden strengths. Another theme is disillusionment. As the story unfolds, they may find out that they are not as important in the grand scheme of things as they thought, like in 'The Great Gatsby'. Here, Gatsby believes he can rewrite his own story and be the main character in Daisy's life, but ultimately faces disillusionment.

Betrayal is a very common theme. Usually, the protagonist is betrayed in their original world or in the isekai world they are transported to, which then triggers their desire for revenge.