Yoake Sayori

Yoake Sayori (夜明細魚) is a Level 4 esper and is a member of White Alligator, introduced in Toaru Kagaku no Railgun SS: Dasoku, Mata wa Toaru Jiken no Shumaku.

Toaru Kagaku no Railgun SS: Dasoku, Mata wa Toaru Jiken no Shumaku
Sayori was one of the four White Alligator members hired to transport the comatose Saitou Souta while Misaka Mikoto and Aizono Mio were distracted by a rumour leading them into a trap, though she and the others had the secret goal of getting revenge on Souta and Mio, jealous of her being the only White Alligator member saved by the counselor. Sayori, Wajiku Kobina and Hyoudou Maki faced Aizono Mio in combat while Sakasama Yuri made sure Mikoto asphyxiated in their oil trap, but despite managing to corner her and almost killing her, the trio were defeated by Mio once Mikoto relayed to her Souta's message and intentions of saving all White Alligator members.

Abilities
Her ability is Military Oil (油性兵装(ミリタリーオイル)), which allows her to control oil and other petroleum products as well as freely change their properties.

Quotes

 * (To Aizono Mio, Railgun PSP SS): "It all started for us when our hopes were cut off in front of us. Surely you can imagine how you would react if he had told you one day that he had had enough and was calling it quits with you. We all experienced that same hell."