can anyone tell what anime this is?

i need help.there this hiển thị i watch but i don't remember the name.it was about these guys who get this letter(that is black,i think) in the mail box to take part in a game
so they have to make 3 person team.if their team wins they get 100,000,000,000,000 dollars if i remember corrcetly.
please help me!