Kumokawa Seria

Kumokawa Seria (雲川 芹亜) is a side character that was introduced in volume SS2. She's Kamijou Touma's senpai, a third year student going to same school as him and is described as a genius. She's currently employed by Kaizumi Tsugutoshi, one of the 12 members of the Academy City's Board of Directors, as his advisor. She's very knowledgeable in things happening on the Science side, knowing about Deep Blood, Imagine Breaker, and the Level 6 Shift project. Personally she's very interested in Touma and his ability Imagine Breaker. To resolve the issue of governments and/or various other agencies from forcibly taking control of natural born espers, or 'gemstones' in SS2, to try and build another esper research facility (even though according to her the chance of them discovering a way before they end up killing the gemstones like lab rats is zero) opposed to Academy City, she proposed using the SISTER clones that's going through adjustment in various parts of the world to collect the 50 or so 'gemstones' and keep them under their protection. It is implied she made some sort of deal with Heaven Canceler in order for the SISTER clones to be mobilized. .

Also in SS2, it is implied Seria knew Kamijou Touma from before his memory loss.

She's also mentioned in passing in Volume 19, when GROUP needed an ally on the Board of Directors to fight against the Director after them they ruled out Kaizumi as a option, since Seria would not be fooled easily and might advise Kaizumi against helping them.

Seria is the main character of a short story named Love Letter Contest (ラブレター争奪戦) found in the artbook Rainbow Spectrum: Colors by Kiyotaka Haimura, in this story she set ups a plan on where she will catch a spy by using a love letter from her to Kamijou Touma, under the logic that the spy will believe the love letter to be an actual important confidential message from Seria to Touma; for this purpose Seria creates a great ruckus and makes it quite know that she wrote a letter to Touma.

At the end of the story not only Kumokawa catches the spy, but it is also slightly hinted that she is aware of Touma's memory loss.