Okay, I'm sure you have learned the barrier jutsus that were once a part of the Ninjutsu list.
(Fuuinjutsu: Kami Komyunikēshon) Sealing Arts: Scroll Communication technique
Type: Supplementary
Rank: B-Rank
Range: N/A
Chakra: 20
Damage: N/A
Description:
The user will create 2 or more scrolls with an embedded sealing formula that connects them all together. As such, anything written in one scroll will appear written in all the connected scrolls. A very useful communication technique, it can connect scrolls regardless of the distance between them. To activate the scroll, the user needs to perform a key of hand seals that will be unique for each creation and only known to those the user wishes, preventing the use of the scrolls by those the user doesn't allow.
Easily explainable, this jutsu is really useful inside the Ninja World. You create two (or more) scrolls and give one to another and keep one. By forming a set of seals only you are the ones who are to be receiving the info knows, you create a message that appears in all linked scrolls, sort of a instant messaging system. After appearing in the scrolls for a moment, the messages fade away.