Kururu Sumeragi is the leader of the current Tool Toul To and Pledge Queen. She has very messy hair, and uses pins in attempt to keep it kempt. She always carries tools around in her clothing. She is Ikki's Tunner and wants to get to know him better personally and in order to tune him better. Although shy around Ikki at first, she becomes devoted to him after witnessing his anger over Simca's attack. She does not wear ATs, but as the leader of Tool Toul To, she is a true genius in repair, construction, and maintenance of ATs. In Ikki's battle with Ringo, Kururu identified the sound of Ikki's ATs, arrived at the battle in time to intercept Ikki as he was falling towards the river, and rebuilt his ruined ATs in midair in less than three seconds. She originally rebuilds the Wind Regalia for him, though it is stolen and given to Sora. During the Fight with White Wolf Clan, Kururu wants to show Ikki her power as a tuner by helping out the other team. Afterwards, Ikki asks her to create the new Storm Regalia for him, a request which she gladly accepts.

It quickly becomes evident that Kururu has feelings for Ikki. During the talk with Kilik and betrayal of Sora, she ran to him and tried to confort him.Later on, she appeared along with Simca and Ringo (under the guise of Croissant Mask) after Kogarasumaru's special training. Agito teases them, saying, "You three came here with intentions of getting a kiss, but you're out of luck, right?" The three deny this accusation, but then reveal they had some similar intentions. During that time, her power struggle with Simca and Ringo over Ikki's affection is seen.

- Road -
Kururu is the current Pledge Queen of the Ring Road, as well as Ikki's tuner. Although she is not a Storm Rider, she is still considered Queen-level for her skills with tuning. Numerous characters on all sides of the war between Sleeping Forest and Genesis have remarked that she is Makigami Ine's successor. Like the other Kings and Queens, she has her own 'shadow', consisting of a singing woman draped in piano mechanisms. first apperance in chapter 109

- Regalia -
As the Pledge Queen, Kururu is able to activate the Pledge Regalia, Axis. It takes the shape of a large cross (larger than Kururu herself) which splits into numerous, thinner crosses interconnected by a large amount of wires. By synchronizing their movements through singing (characterized as bird calls by onlookers), all tuners connected to Axis are able to access Kururu's immense tuning prowess, including Infinite Scale

- Tricks -
Infinite Scale - As the Pledge Queen, Kururu is able to access the world of "Infinite Scale". This enables her to repair, modify and/or tune any ATs in a matter of seconds. Other members of Toul Tool To have remarked that this level of repair work is actually painful to the eyes and hands, although Kururu has shown none of these side-effects.