K-On:Yui's Journey.

K-On!:Yui's Journey (けいおん!：唯の旅, Romanji:Ke ion! Tada no tabi) is a sprite edited Japanese localization of Sonic the Hedgehog (16-bit) where Yui Hirasawa replaces Sonic as the protaginist.

Trivia

 * This is the first K-On!-based retooling of a Sega game for the Japanese market.
 * This isn't the first instance of a game being retooled for a specific market. Tec Toy retooled a sizable amount of Sega games for the Master System (and Wonder Boy in Monster World on the Genesis) in Brazil.
 * The title screen music is a 16-bit remix of the K-On! anime theme song and it is used in the K-On! retooling of Sonic the Hedgehog 2 (16-bit).