Fūinjutsu

Fūinjutsu (封印術;  Sealing Techniques) is the umbrella term for techniques that can seal objects, chakra or even living beings inside another medium. Fūinjutsu is considered an often overlooked art among shinobi; learning it is a tedious process, and in many situations it cannot always be used to its fullest extent. When the situation does arrive, however, users of fūinjutsu are given a great advantage over their opponent. The basics of sealing allow the user to seal small amounts of items into paper, but more experienced users can seal and unseal a small army’s worth of weapons, chakra and people into whatever medium they wish.