Takani Megumi was the last person left after her whole family was killed.She became apprenticed to a doctor and soon dicovered that the doctor was making opium for a man that was called Takeda Kanryuu. Afterwards, she was forced to learn how to make opium and distribute them. She had wanted to end her life for killing others but somehow never succeeded. Kenshin and the others find out and help save her. Now she is a local doctor trying to save lives and is also very good at it. She took the advice from Kenshin, that helping others replaces the lives they had once took.
Although she seems to like Kenshin, it is more to annoy Kaoru then real feelings. It is more likely that she likes Sano. The chicken head. She in fact often helps Kaoru get together with Kenshin. When Kenshin left, it was Megumi who made Kaoru go after him to give him the medicine. Yelling at her that she was the one that he said goodbye to. And in another scene, when Megumi and Kaoru are under a bridge, Megumi tells Kaoru to encourage and believe in Kenshin. Using the excuse that if he ever got hurt like that, Megumi might not be able to save him.