Talk:鬼蜘蛛ト狐ノ獅子ト (Onigumo to Kitsune no Shishi to)/@comment-76.67.7.167-20171206015337/@comment-32327493-20171222183810

The songs themselves don't detail how Mai became a cannibal explicitly (The Fox's Wedding is the closest thing to it), but Masa's blog does. Essentially, Mai was kidnapped when the Shishikusa's mansion was attacked. She was abducted by the Oborodzuka clan (aka Akari's) and was forced to eat raw human flesh. She may have been possessed for a short time as well. Eventually, she became a full-fledged absolute madman and ate her parents on her 18th birthday. Cannibalism is part of the curse Akari put on Ryou and her family, as well as becoming a psychopath and "being in the land of the dead while still alive" aka being able to see the ghosts of people they've killed. It didn't have enough time to take effect on Ryou, since she was murdered by her daughter shortly after.