Leaf is a Japanese visual novel studio under the publisher Aquaplus, and has offices in Yodogawa-ku, Osaka, and Tokyo. It and its competitor Key (to which it is often compared) are two of the most popular and successful dedicated visual novel studios operating today.[citation needed] It was launched out of obscurity by its early release To Heart.[citation needed] Leaf used the XviDvideo codec in several games: Aruru to Asobo!!, Tears to Tiara, Kusari, and ToHeart2 X Rated. Since XviD is free software, released under the GPL, Leaf was obligated to release the source code to those games under the same license.[1][2][3] One still requires the game data to actually play the games with the source code.[4][5] In addition, a free software game engine, named xlvns, was developed soon after Leaf released its first three visual novels.[6][7] Characters from Utawarerumono, Tears to Tiara, To Heart, and Kizuato are playable in Aquapazza: Aquaplus Dream Match, a fighting game developed by Aquaplus featuring characters from various Leaf games.[8]
