ココロ (Kokoro)

Background
The song tells a story about a robot (Rin) made by a lonely scientist, but is missing a program unable to be made: a heart. Some time after her creation, her scientist passes away, leaving her alone for several hundred years. She begins to wonder about her creation and makes a wish. She accesses the files that her creator had left and finally gains a heart. In the process, she discovers what it's like to be happy and sad. With her new feelings, she gratefully dedicates all of the songs that she sings to her creator. In the end, the miracle robot had a short in her system and could no longer sing. However, she had a smile on her face in her last moments, resembling an angel.

A sequel named "Sayonara Arigatou" was made for the album of the same name. It tells the story of the robot's creation and the making of the heart told from the scientist's (Gackpo) point of view. He explains that he had felt lonely but when he made the robot, he was finally able to love someone and he wants to give her the same thing she gave him, a heart. But creating it takes such a long time that by the time he is finishing it, he's dying of old age. He begs her to smile for him and wants just a little more time to say "Thank you".

This song is featured on the compilation albuma EXIT TUNES PRESENTS Vocalostar feat. 初音ミク and KARENT presents TIME TO SAY HELLO! feat. Hatsune Miku, among others.

Concerts
This song was featured in the following concerts.

Stage Play
Katsuyoshi Ishizawa, Redjuice.
 * Official Nicomu site

Sheet Music Publications
Piano sheet music appeared in the Piano Solo Yasashiku Hikeru collection. This song has also appeared as sheet music in the VOCALOID Best Selection series.

Novel Adaptation
Toraboruta-P announced that on April 27, 2012; (previously it's stated to be April 17, but it was delayed) he will release his novel entitled "Kokoro", a novel based on the song.
 * Official Website

The novel is written by Katsuyoshi Ishizawa and illustrated by Nagimiso.SYS, an illustrator most notable for his PV of "Roshin Yuukai" also a card illustration by redjuice. The price is 1,200 yen and was available for purchase in Amazon on April 27.

A crossfade of the novel ("Kokoro" arrangement by Toraboruta-P and video by Nagimiso.SYS) can be seen on niconico and YouTube. A month after the novel was put on sale on Amazon, it was announced that the "Kokoro" novel had sold out and could no longer be purchased from Amazon. There is currently no news of a second wave of printing; it has sold faster than expected.

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