There is a wide variety of powerful weapons in "Beast of Reincarnation." Oboro is one of the most useful among them. To obtain Oboro, go to the teleport point on the upper level of Matsukawa Development Area in the Matsukawa District of the Mountain Region. After exiting the teleport point, walk straight and take the elevator down. You can pick it up directly in the prison area.
How to Obtain the Oboro Weapon in Beast of Reincarnation