Misa Amane is a famous Japanese model. Her parents were murdered and the man suspected in the crime had a long and drawn-out trial. Rumors then began to surface that the murder suspect may be innocent. Misa now devastated, saw her chance at justice slowly slipping away. Suddenly sometime during the trial, the murder suspect was killed by Kira. Misa felt extremely grateful and wanted nothing more than to meet Kira and thank him. One night while Misa was traveling alone a crazed stalk approached. He confessed his love for her and asked that the two of them be together forever. Misa rejected him which caused the stalked to cry hysterically and pull out a knife. Before he could attack the individual dropped to the ground and died. Her interest in Death Note, and Light Yagami, is directly influenced by these two events.
The shinigami known as Rem would later give Misa a Death Note of her own, and reveal that it was a shinigami named Gelus who saved Misa from her stalker. Misa, now with a notebook of her own and a pair of shinigami eyes, set about to follow Light's example and kill criminals. She became the "second Kira."
Misa wanted to contact Kira to thank him, so she sent him public messages with hidden meanings only he could understand. She got Kira to meet her, but she didn't immediately reveal herself to him. It was when Misa laid eyes on Light Yagami that she fell hopelessly in love and would from then on devote herself to him. Misa appeared at Light's house and explained to him who she was and why she wanted to help him. Light saw the unquestioning loyalty and love Misa had for him and realized he could use her and her shinigami eyes in any way he saw fit. He agreed to be her boyfriend, and the two remained "together" for the rest of the series.
Light would soon discover that Misa was not without her faults. Her mistakes would land them both in solitary confinement under L's supervision. Light and Misa were forced to give up their memories of the Death Notes. Despite this huge blunder on her part, Misa would prove to be quite useful when she went undercover and got a confession from the new Kira, Higuchi. It was thanks to her that L and Light managed to catch Higuchi, and Light was able to recover his memories. He sent Misa to regain hers as well, and it was thanks to Rem's love for her that Light managed to maneuver Rem into killing L.
Lesser Role & Death
Misa's role in the series would shrink after that. Her few appearances were brief, generally showing her killing criminals until Light asked her to give up her memories again. Light would ultimately make fatal mistakes, and in his last moments, he called for Misa's help, forgetting in his pain that she was no longer a Kira and she was safely home in their apartment.
Misa Amane committed suicide soon after Light's death.