Level 5

Level 5 (超能力者 (レベル5) ) is currently the highest esper level to be accomplished in Academy City. Only seven out of the 2.3 million students participating in the Power Curriculum Program have officially achieved this rank, indicating the level of difficulty involved in reaching it.

All of the currently known Level 5 espers have been attributed a nickname that is either the name of their esper ability or related to it. Currently, Accelerator is known solely by his nickname.

Characteristics
Level 5s are espers that hold tremendous amounts of esper-related influence and power, possessing capabilities far above any other esper with similar abilities. The abilities of a Level 5 esper are so powerful that their primary applications are banned from being used in the Daihaseisai.

Furthermore, because the Power Curriculum Program is part of Academy City's curriculum, the strongest of Academy City's espers, such as the Level 5s, are most likely to also be honor students. This is displayed by Mikoto, who had enrolled into Tokiwadai Middle School, and is one of its top students, as well as Accelerator. The Level 5s, apart from their peers, have specialized analysis and research facilities created for them, for example, Accelerator being part of the Special Ability Institute, Dark May Project, and many more.

They most likely get paid with the most money amongst their other esper peers as part of the curriculum's payment program for the espers as being part of the experiment.

Also, it seems that Academy City views Level 5 Espers (and others in general) as a threat, due to the fact that their developing minds can make them act based on emotions rather than logic. In order to rest easy, they have created Rensa, a cyborg that can use the abilities of the #1 up to #6 in order to deal with them in the case they decide to go against the city, and she supposedly can defeat all seven of them.

The ranking of the Level 5s is dependent on the worth of their abilities to the ongoing researches rather than based on the level of their power. Their counterparts are the Saints from the magic side.

Personality
A particular object of notability of all the Level 5 Espers is a recurring instance of mental instability, be it comedic or serious. Mikoto, the first Level 5 seen in the series, has a comedic obsession with defeating Kamijou Touma, although she has been referred to as the sanest one out of all the Level 5s. Sogiita Gunha believes himself to be an ally of justice and purposely acts in accordance of superheroes in fiction. Accelerator, Kakine Teitoku, Mugino Shizuri, and Shokuhou Misaki all demonstrate more sociopathic or psychopathic tendencies with the willingness to hurt people on a whim, though this may be more related to their background more than anything else. However, both Accelerator and Mugino have become less violent lately because they feel guilty about all the harm they've done. Misaki has also demonstrated that she does care about her friends and is willing to go out of her way to save them.

Due to this, only Mikoto is the one apparently competent enough to be used as a marketing mascot or demonstrator for Academy City. Even then, it is not unheard of for any of the Level 5s to be requested for demonstration.

That said, the essay The Wall Between Level 3 and Level 4 from Toaru Majutsu no Index no Subete seems to reject this premise, stating that gaining high level powers like Accelerator and Mikoto did is the result of having strong minds and firm ideologies and principles.

In addition to this, many of the Level 5s are not on good terms with each other, although they would still sometimes form alliances if the situation called for it.