Transmigrating to a Magical World: My Little Sister Is a Yandere

Lu Yuan drowns while trying to save a little boy from drowning. When he opens his eyes again, he finds himself in a place called the Huanli Continent, a land full of magic where some things are similar to Blue Star, such as cameras and days with 24 hours (and clocks).

After absorbing the original owner's memories, he learns that the man had an adopted younger sister whom he had abused for years. Lu Yuan secretly vows to treat her well.

As they spend more time together, his sister lets go of her past resentment and forgives him.

Just as they're settling into a peaceful life together, people the original owner had offended show up and beat Lu Yuan so badly that he's left gravely injured. When his sister returns and sees the blood, she thinks her brother has been murdered.

From then on, she begins desperately searching for him, and her mind grows increasingly twisted and obsessive.

Only having her brother by her side can keep these feelings in check. Before long, she finds him at a magic academy.

When they meet, Lu Yuan tells his sister that he transmigrated. She is very clever and had already guessed that the man before her was no longer her original brother.

After they finally put their estrangement behind them, their relationship changes in unexpected ways...

[The heroine's obsessive nature develops gradually. It may not be obvious at first, but by the middle and later parts of the story, she becomes extremely obsessive.]