0verflow is a Japanese video game division of Stack Ltd. specializing in the production of mature interactive fiction. The Overflow label is known for its game franchise School Days.

In 2012, they announced that Shiny Days would be their last title as a developer, but that the company wasn't bankrupt and game support would continue. Ultimately, Shiny Days wasn't their last game as they released Island Days and Strip Battle Days 2 in 2014 and 2016 respectively.