music in the game was composed by Toru Minegishi, Manaka Tominaga, and Asuka Ota. Minegishi wrote the main overworld music and shared the work on field, character and event themes with Tominaga. Series sound composer Koji Kondo contributed the ending theme, while Ota was responsible for some of the music in the multiplayer mode. The concept for Spirit Tracks came to Aonuma while he was reading a children's book to his son. The book, titled Senro wa tsuzuku, concerned a group of children creating a railway line in a magical countryside region. Iwamoto felt that Spirit Tracks should not be too like other Zelda titles, citing an argument that occurred that the train was not a good fit for the series, splitting the staff between those who thought the train should be changed, and those who successfully fought to keep the train. Aonuma felt that the team had created new ways of playing, while retaining several elements from the series. Aonuma commented that because the puzzles were designed by a designer who was formerly a programmer, they felt different to him. The use of the train was fixed early on, but the concept of players building train tracks was discarded as Aonuma saw it as a "nightmare" to manage. The Tower of Spirits was originally going to function the same way as the Temple of the Ocean King from Phantom Hourglass, requiring the player to climb the tower each time they restore a new floor by going through the tower again from the bottom until they reach it. As development neared its end, Anomua made a comment about this never giving the feeling of climbing a tower, resulting in the spiral staircase included in the final design. Using feedback from Phantom Hourglass, the team adjusted the controls so players would find performing Link's actions on the touchscreen easier. They also removed elements that had met with negative feedback from players, such as the time limit imposed on players when going through the previous game's main dungeon. The Spirit Flute was brought up early in the game's development. Because the microphone capabilities were featured so prominently in the game, the team decided to incorporate it into the flute. At an early stage, the team decided to focus on the ability to control and work cooperatively with a Phantom, originally used in Phantom Hourglass as a Wi-Fi battle mode-exclusive character. In questioning