INSANITY is one of the few songs that are mistakenly attributed to Dir En Grey, despite being from another band.
In this case, the song was created by Vasalla, a Japanese rock band that existed even earlier than Dir En Grey. At one concert during Dir En Grey's early days, they covered this song. More specifically, this happened on September, 1997, on the last date of the Dir en grey presents MAZOHYST OF DECADENCE SHOW tour at Meguro Rockmaykan. At the same concert, they also covered 親愛なるDEATHMASK by 黒夢 (Kuroyume) and X by X Japan, both with Vasalla. There exists a live recording of Dir En Grey's INSANITY cover, but it's only available to tereko traders. However, you can listen to the original version by Vasalla here.
Dir En Grey would later provide background vocals for Vasalla's 月神~Artemis~.