In Kingdom Hearts Chain of Memories, Drain is an enemy card effect that allows Sora to regain HP when striking enemies with attack cards, in exchange for enemies dropping fewer items. It costs 35 CP to add to the deck and lasts for one reload.
In Kingdom Hearts Birth by Sleep, Drain is a Dimension Link ability that allows the user to drain HP with every attack that strikes an enemy.
In Kingdom Hearts 3D: Dream Drop Distance, Drain is a magic command that gives one ally the Drain status for 10 seconds.
Kingdom Hearts Chain of Memories
Kingdom Hearts Birth by Sleep
Kingdom Hearts Re:coded
Kingdom Hearts 3D: Dream Drop Distance
There are weapons and abilities in the Final Fantasy series with similar effects to Drain in Kingdom Hearts, such as Drain Blade.