Megumi comes from a long family line of wealthy medical doctors. However, her family supported the Tokugawa Shogunate, and during the Meiji Revolution they were sent to aid the Shogunate against the Imperialists. By the end of the war, Megumi was the only survivor of her family, and her house and name were brought down just as the Shogunate had been.

In memory and hopes that some of her family might be alive, Megumi entered into the field of medicine - her only link to her past. Unknowingly, she apprentinced under a doctor who was involved in an illegal opium ring for a businessman named Kanryuu Takeda. When that doctor was killed, Megumi was forced by Kanryuu to continue making drugs, even though she hated the twist of fate her life had taken.

Megumi eventually discovered that Kanryuu was devising a way to mass produce the drug, and in a vain attempt to escape, she managed to run away. While away from Kanryuu, she met Kenshin, Sanosuke, Kaoru and Yahiko, who all taught her that life was worth living despite the past. But when Kanryuu and his guards (Aoshi and the Oniwaban) caught up with her, Megumi was dragged back and the Kenshingumi were forced to fight.

After Kenshin wins the battle against Kanryuu, Megumi is set free. With Kenshin's help, she decides to repent for her past and becomes an apprentice under Dr. Genzai. Within a short time, Megumi builds her own very reputable medical practice in Tokyo and is happy to help people instead of hurting them.