Medusa

Where to find

Trial of Time - 5th FloorTrial of Darkness - 7th Floor

Also listed for

Maps whose monster list names it without a placed spawn.

Trial of Darkness - 3rd FloorTrial of Darkness - Top FloorPenguin BeachRocky Hill Shrine

Monster book

The game keeps its monster book text in Japanese only. The text table exists in nine language copies, one per release language, and all nine hold the same Japanese entries, so the game files contain no official English text for the book. This site doesn't write its own translation of game text, so the entry is shown in Japanese as the game has it.