Lance K. Kuroi, also credited under the names Ransuke Kuroi and Lance-K Kuroi, is a Japanese author known for originating the Savanna Game series. He was born on February 3, 1987, and was residing in Tokyo as of the early 2010s. Prior to his career as a published novelist, he worked at an advertising agency while writing fiction in his spare time. Kuroi began his writing career by publishing serialized novels on mobile phone platforms, a popular medium for digital literature in Japan at the time. He started writing under the pen name LANCE in March 2009 on the Mobage platform.

Kuroi is best known as the creator of Savanna Game, a suspense battle fantasy novel. The story follows a young man named Kazuya Shibuya, who receives an anonymous invitation to a state-sanctioned killing game designed to motivate the apathetic youth of modern Japan. Along with two friends, he must fight in bizarre battles that traverse the space-time continuum, pitting him against adversaries ranging from dragons to the Shinsengumi of the shogunate era. The novel first gained significant attention as a mobile phone novel on the community site Everystar, where it accumulated over 15 million reads within a single year. This success led to its acquisition by Shogakukan Creative, which published the first printed volume of the novel on November 19, 2011.

The popularity of the original novel led to multiple adaptations. A television anime adaptation was officially announced in December 2011, with production expected to begin in 2012. According to announcements at the time, Kuroi himself confirmed that the project had been green-lit. Additionally, a manga adaptation of Savanna Game was launched in 2012, with Kuroi credited as the original story author and Eri Haruno as the illustrator. This manga was published by Shogakukan and later released in Brazil by Editora JBC. Beyond his debut work, Kuroi also wrote another novel titled Blackout (or Blackout GAME), which he began serializing in June 2010 on the Everystar platform, where it achieved the number one ranking in the site's overall rankings among 680,000 works.

In the context of the anime and manga industry, Kuroi represents a wave of creators who emerged from the mobile phone novel scene, achieving mainstream publication and multimedia adaptations directly from digital success. His work, Savanna Game, incorporates recurring themes of survival, state-sanctioned violence, and historical fantasy, blending contemporary social critique with supernatural and time-travel elements. While the announced anime adaptation of Savanna Game did not materialize as initially planned in 2012, Kuroi's profile remains significant as an example of a digital-first creator who successfully transitioned to traditional print publishing and secured major adaptation deals early in his career.