There was once a scientist, who was born near the time of extinction for humans. There were very few humans indeed, and only about one thousand were left. The boy understood this well, and knew humans would die out soon. He wanted, however, to make his life count, to leave the world somthing behind when they were gone.
There were still plenty of books left, though no schools existed anymore. The boy went to the abandoned library, looking for his purpose. He went to the science section, the engineering section, and the mechanics section, picking out the best books he could possibly find, and carried pile by pile home. He no longer lived with his parents, they had died long ago. The boy was only 12 years old, scrawny, yet extremely bright. Perhaps, he mused, he would have been able to prevent this all from happening had he been born centuries earlier. He read through all the books, for his mother had taught him to read at age 5. He read day and night.
He finally decided on a single project, which he named 'Project Kokoro'. The boy began working without rest, for days and months on end. After about a year, he completed his project. He had made a body out of artificial skin and bones, which was able to move and walk just like a real human.
Only one problem remained: the android was unable to comprehend emotions; she had no heart, no 'kokoro'. She could not enjoy that she was the only one of her kind, nor could she express her sorrow for the same fact.
She could sing, and often the scientist and his creation would go to sit under the cherry tree, the scientist would bring out his sheet music, and teach her to sing. Her singing was automatic, though, without emotion. There is no music without heart. "Rin! No, you must-" the scientist would always begin to admonish, but stopped. What was the use? Rin couldn't understand his feelings. Rin couldn't understand anyone's feelings, no matter how much she wanted to.
Rin, indeed was what the creator called his creation, after his late mother. The scientist couldn't recall how his mother had looked like, so he made Rin a female version of him instead.
Bit by bit, the scientist began researching ways to make her heart, to make her feel. But still, all the words which came from her lips were choppy and robotic, emotionless. He was thirty by the time he started getting farther into his research of Rin's 'Kokoro'. Rin brought him food every day, but she didn't have human sense to tell her master, her creator, to got to sleep.
One day, the scientist became ill. "Incurable disease: State: Fatal." Rin read from her computers in her head. She expressed no emotion to the sight of the blood the scientist held in the palm of his hand, blood which he had coughed out himself. The scientist simply nodded, and went back to work.
Finally, he had completed the 'Kokoro'. The program was unstable, but nothing could be done now. As if his body understood, his feet led him to the cherry tree, bringing Rin along. His systems began shutting down, as did his organs. He smiled sadly at Rin, and whispered harshly, "Do not... activate the 'Kokoro'." he gasped, his breaths getting shorter. "But.." He looked into her eyes. "If you do, Rin, I..love..you..and..sing for me.." And with that, the scientist died next to his beautiful, emotionless creation.
A few centuries passed by slowly, Rin was alone without her master, for he had not made any other creations but her. She passed the computor many times, and finally pressed the button to activate 'Kokoro'. As the program began to install, she was hit by a flurry of emotions. She began to cry and laugh, singing her heart out. All this time, she regretted not being with the scientist, for not loving him or even liking him. Rin skipped to the cherry tree, and laid down into the fallen petals. Finally understanding that her master wanted to give something back to the world. He wanted to give them the gift of song. The gift of love.
Rin began to short circut, but she wasn't worried. She had completed her inherited mission. She died with a smile on her face, looking as sweet as an angel. For she knew, she knew, she had been given the gift of life.