Takitsubo Rikou

Is a member of ITEM. She suffers from brain damage after fighting and being defeated by Teitoku Kakine in vol.15; as a result, she can no longer use her esper abilities. She was developed through such a way she can only use her ability by consuming the essence, as part of a earlier project to create a Level 6 before the 'Experiment' involving Accelerator, and thus she can no longer be developed through 'normal' methods other espers go through.

In her fight against Kakine in vol.15, she supposedly tried to manipulate his AIM field as a attack against him, forcibly attempting him to lose control of his power and berserk, and also attempting to use his own ability against him. Though due to her condition and the difference in their power she still lost.

She arrived to Russia with Hamazura Shiage after hijicking a jet from Academy City on the District 23, after that her condition gets worse and is handed to a doctor only to know that she can't be healed with the current techonoly from Russia. Later Shiage tries to hide her while fighting against pirates next to a villager and a soldier.

Abilities
Her ability was the AIM Stalker which she uses to track down the esper, she needs to consume what's called Body Clear' in order to use her power, however continued use of the drug has worn her body down to the point she would break down if she uses it again once or twice.

She also states that her ability allowed her to steal other espers' abilities by memorizing their AIM, potentially allowing her to become the eighth Level 5 esper in Academy City. This fact was also mentioned by Kakine after their fight, saying it's such a shame she had to rely on the essence to use her powers.

Trivia

 * It is uncertain if Body Clear, the drug she uses to use her abilities, is a by-product of Telestina Kihara's research. However, both Body Clear and Crystallized Esper Essence seem to have the same effect on the user, and is also in the same form of medication.