Piano Hutan (Piano no Mori: The Perfect World of Kai (ピアノの森 – The perfect world of KAI, lit. "Piano's Forest")
Synopsis
by 
tells the story of Kai Ichinose. He is the son of a prostitute named Rei Ichinose who lives in the outskirts of the forest. He went to school with Ajino Sousuke as his famous music teacher does not like small children. Kai likes to ditch and often fight with school friends who often mock him. Kai was born as a beautiful-faced boy and was not always accepted because of his mother's status. When he was a toddler, Kai once climbed a tree, which is next to his residence, through his window. He fell and landed on a piano in an abandoned forest (which turned out to belong to Ajino Sosuke when he was still a famous pianist, before he had a car accident that claimed his fiancé's life and injured his hand so he was forced to retire early). Kai considers the piano as his personal toy and plays his keys every day and over time is able to directly play the songs he just heard for the first time perfectly.
Kai then got acquainted and made friends with Shuhei Amamiya, son of renowned pianist Yuichiro Amamiya. They also often play into the forest to play the forest piano and Shuhei was very fascinated with the game Kai which is the result of self-taught learning without ever learning from a teacher. Ajino had heard the news that a forest piano could be played (although he could not play it anymore, possibly because the length of time he did not practice the piano caused the strength of his hand to decrease) and eventually found Kai playing the piano. Ajino then tries to polish Kai's extraordinary talent in order to become a better pianist than he was when he was young. As the story progresses, Kai meets many friends and rivals who help Kai evolve.
This manga has a timeskip that confines the story when Kai was a kid and the story when Kai was 17 years old and ready to move into the world of global music.
The manga was made by Isshiki Makoto and the Indonesian version was published by PT. Elex Media Komputindo. The story of this manga was finished in 2015 with the release of volume 26.
The Forest Piano was once adapted into a film in 2007 and directed by Masayuki Kojima.
The Forest Piano will be adapted into a television series (anime) in April 2018 and broadcast by NHK.