Also known by the pen name Hagane Tsukishio, Kotaro Uchikoshi is a scenario writer known for his work on visual novels and adventure games. He initially worked employee at KID from 1999 to 2004, starting work as a graphic designer on Pepsiman and then moving on to write the first two Memories Off games and the Infinity series. Some of his most most highly acclaimed work during this period was his work on the Infinity series, with his most famous title being Ever 17: Out of Infinity.
After the release of Memories Off 2nd in 2001, Uchikoshi left KID and became a freelance writer, although he still worked on several titles with the company. In 2007 Uchikoshi was invited by Jiro Ishii to join Chunsoft, where he created the Zero Escape franchise starting with 999: Nine Hours, Nine Persons, Nine Doors in 2009 and Zero Escape: Virtue's Last Reward in 2012. Both titles would go on to be unexpectedly successful overseas, helping to expand the audience for visual novels in the Western world.
In 2013 he co-wrote 5pb's visual novel Steins;Gate: Linear Bounded Phenogram, along with Steins;Gate creator Naotaka Hayashi, another highly acclaimed writer he has previously worked with on Remember 11 and 12Riven.
In 2018 he announced he was leaving Spike Chunsoft to start a new studio called Too Kyo Games.