A woman had reincarnated into another girl's body who was already a young adult. She just woke up and realized that she was in a new body and had memories of her past life. I think this new girl's family was well off.
The setting was a couple of years after the female lead was murdered. In her past life, she was I think a knight or like a queen, I’m not sure, but she did wield a sword and fought. She particularly had someone in her group who she was familiar with and trusted 100% and he always went into battles with her. He was her second in command. This guy loved her and admired her, but never confessed and I think he was send on a mission out of town when the female lead was murdered, so he lived with the guilt of not being there with her.
There were scenes where the guy felt like she resembled the female lead of the past that he knew by the way that she acted and seemed to know of locations that only him and her knew. For example, the girl had been invited to a ball in the kingdoms, perhaps the palace, and she went but got overwhelmed, so she entered a chamber/resting room where she had always gone in the past and that's when the guy saw her.
Another scene is where the female lead entered these underground tunnels/passageways beneath the palace, searching for a secret room that only she and him knew. That's where they always planned their strategies/plans and he heard a noise, so she scurried to get away, only to be caught by him and asked what she was doing there. She said that she had gotten lost and that's when his suspicion of her grew, because she knew things only they would know.
I think it might have been a one-shot, or at least have a couple of chapters, but I think there was a novel it was based on.
