Chekov's Spell -- This spell has a two-fold effect. The first is to make the target item almost-unnoticeable to anyone not specifically looking for it. The second is that someone who has seen the item will remember it when they encounter a situation that would be perfectly solved by use of said item.
Trapped in his tomb, but alive, the God of Pain awaits his uleashing, said to be at the end of the world, he uses his only powers he can and calls to him 2 people, a man and a women to reliquish him from his prison. The man and the women, decieved by them thinking it a person trapped, go after to help the God of Pain unwittily and let him destroy the world