An 'Iris' is a power that the majority of people in the Iris Zero series are born with. It is an ability that allows the user to see different things, depending on different factors.
People with an 'Iris' are able to see a variety of things from 'former lives', 'love affections', 'probability' and to even being able to see 'a person nearing death'. The possibilities are endless but a person can only possess one kind of Iris and each Iris has its own unique ability that differs it from the rest.
People with an 'Iris' can't see their abilities through a screen i.e. video chatting through cell phones.
In the Iris Zero series, the first generation of people that were born with the Iris power was estimated to be 27 years before the main storyline takes place. The probability of being born with it then was only 1%, 22 years after that though, the numbers increased tremendously and reached about 99% of the population.
This power, unfortunately, split the world into two parts; between the younger Iris generation and the fully grown adults, who do not have that power. Adults have a hard time understanding the younger generation now because of how different they are from them due to their abilities. This has been mentioned a few times in the series; both parents and teachers who do not have an Iris stated that they were having difficulties while trying to understand the way these children think and act.
In the new generation of people that possess the Iris power, there are also people among them that do not have such a power (the 1% proportion). Those people are commonly called 'Iris Zeros', meaning that they have no Iris at all. Here, again, the world was split into two: between 'Those who have an Iris' and 'Those who don't' (the Iris Zeros).
Many of the Iris Zeros are not accepted by people their age and younger Iris Zeros are often bullied by classmates or generally children their own age. A lot of people would avoid an Iris Zero, thinking of him/her as a 'bad influence' or under certain circumstances, thinking that him/her not having an Iris was contagious.
|Qualification Iris||Koyuki Sasamori||The Iris to show who are qualified in the form of an 'O' or 'X' appearing over the subject's head.|
|Near Death Iris||Hijiri Shinozuka||This iris allows the user to see black butterflies around a person who is near death or is going to die in the close future.|
|Lying Iris||Asahi Yuki||The ability of this Iris allows the user to see when people are lying, by seeing the liar grow a devil's tail out of their behind.|
|Emotion Iris||Nanase Kuga||The ability of this Iris allows the user to "see someone's emotions" by the colour of butterfly wings on the person's back.|
|Happiness Iris||Satsuki Tachibana||The ability to see the subjects amount of happiness depending on how much a flower in the subjects heart is healthy or grown.|
|Danger Iris||Katagiri||The ability to see danger.|
|Love Affections Iris||Harumi Tokita||The ability to see one's "love affections" by a ring over the subject's head, connected to an arrow that points to the one they love.|
|Probability Iris||Hoshimiya Rei, Hoshimiya's brother.||The ability to see the probability of an event or action, around objects, buildings and people, by seeing a number percentage.|
|Key Iris||Sakura Misaki||The ability to see someone or something who is the reason or "key" to triggering an event or action to take place.|
|Vocation Iris||Miss Fujimura||The ability to "see people's vocation's".|
|Label Iris||Houjou||The ability to see "labels" on somebody, each one depicting what others say or think about you. (I.e: Cold-hearted, Funny.)|