HIMMEL

HIMMEL (ヒンメル Hinmeru) is a secret area accessible through a locked door in Dritter Stock, and the only way in and out of IBF. Not even Sora is allowed to open the door, and the manual opening mechanism has been disabled by the time Takeshi and the others attempt to open it on May 6, 2017. Fortunately Yoichi Tanaka, who stayed behind after Tief Blau spread through IBF and over, unlocks the door shortly after.

Sora's data, as well as LeMMIH, have home in HIMMEL. Anything that happens in LeMU is recorded here.

Trivia

 * "Himmel" means "sky" or "heaven" in German. This refers to both it being where Sora's data is stored, and a reference to the writing on the stone on Insel Null: "Where is heaven? Above the sky, and at your feet..."
 * "HIMMEL" backwards is "LeMMIH", the supercomputer in charge of Sora.