Rune

Rune is stern, pragmatic and strongly protective of the Regalia entrusted to Tool Toul To. He treats those devices as irreplaceable technology rather than personal property that a frustrated tuner or rider can discard at will.

His response to threats against a Regalia can be severe. When Hako Isawa considers throwing away the newly constructed Wind Regalia, Rune states that he would be prepared to sever her arm to recover it.

That harshness reflects his role as one of Tool Toul To's senior members. Rune has lived through considerably more of the A-T world's history than tuners such as Kururu Sumeragi, giving him a different perspective on the value and danger of the King's equipment.

Rune is a first-generation Gravity Child, placing him among the enhanced humans created through the earliest bioengineering program associated with the Air Treck world.

His body contains numerous mechanical components, and he routinely carries concealed weapons. The full capabilities of those modifications are never explored as extensively as the Roads and Regalia of the series' major combatants.

Rune is also an experienced member of Tool Toul To and therefore possesses advanced knowledge of Air Trecks and Regalia. He once held an unidentified Regalia, but its Road, abilities and eventual fate are not established clearly enough to assign them.

Rune appears as one of the senior figures within Tool Toul To once the organization becomes directly involved in Kogarasumaru's development. His position helps establish that the group has its own hierarchy and history extending far beyond Kururu's relationship with Ikki.

As second-in-command and its oldest member, he provides continuity between the Gravity Children and the tuner organization that services the Kings. His existence also demonstrates that the categories are not completely separate: a Gravity Child can occupy a technical role rather than becoming a conventional King.

As Tool Toul To abandons strict neutrality and increasingly supports Kogarasumaru, Rune remains part of the organization while Kururu assumes the Pledge Queen's responsibilities.

Kururu Sumeragi becomes Tool Toul To's Pledge Queen and Rune's organizational superior despite being much younger than him.

Ine Makigami is the former Pledge Queen whose leadership precedes Kururu Sumeragi's.

Hako Isawa draws Rune's anger when she threatens the Wind Regalia, prompting him to make clear that protecting the Regalia takes precedence over sparing the person endangering it.

Itsuki Minami becomes one of the principal riders supported by Tool Toul To once the organization moves away from strict neutrality.