Arataka is the sword of Sakura Xadium Aino. She originally came into possession of it during the steam era during her time as a member of the Shinguuji Clan. She later reforged the blade into crysteel, spending time with the ancient Ashalan race to learn their secrets. The blade has been sharpened to a mono-molecular edge, and due to Sakura's bond and learned connection with crysteel, she is able to alter its shape given time and concentration.
After her time in Soul Society as the interim captain of the 5th squadron of the Gotei 13, Sakura is now able to achieve shikai and bankai with it.
Noriko Marianna Xadium has also used Arataka on occasion, most notably as a means to threaten Yaijinden, whose emergence occasioned Arataka's reforging, though its shikai and bankai are Sakura's exclusive province.