Hisui

Hisui is a fierce woman whose motivation to fight is to find a moment wherein she can die. During a training session to promote her into the ranks of Ura Uruha wherein the trainees had to fight in the dark with a mask to silence their voices tied around their mouth, Hisui ends up killing her own boyfriend. After getting Kaoru to fall in a river, she challenged Fūko to a duel. As Tokiya left to search Koganei, Fūko fought Hisui in a very dangerous death duel. Fūko came up victorious and also prevented Hisui to commit suicide. She told Hisui on the futility of throwing one self's life away. As a token of gratitude, Hisui lent Fūko one of her weapons, Shinryo Shintō. After learning her boyfriend's death was actually orchestrated by Mori Kōran and that he enjoyed the event as it happened, she defects from Uruha. She is killed by Mori Kōran while she was protecting Fūko. 

Source: http://flameofrecca.wikia.com/wiki/Hisui

Abilities

She wields the madōgu Shinryo Shintō, a pair of blade-tonfa that can elongate and contract at will. After being defeated by Fūko, Hisui gives one of them to her.

Hisui with Shinryo Shintō

Hideki, Hisui's boyfriend.

Shinryo Shintō extended

Shinryo Shintō using to cut down stalactite.