Leaf is a Japanese visual novel studio under the publisher AQUAPLUS (アクアプラス), and has offices in Yodogawa-ku, Osaka, and Tokyo.
Leaf used the XviD video codec in several games: Aruru to Asobo!!, Tears to Tiara, Kusari, and ToHeart2 XRATED. Since XviD is free software, released under the GPL, Leaf was forced to release the source code to those games under the same license. One still required the game data to actually play the games with the source code.
A free software engine called xlvns was derived from this source code.