The Millennial Blade S12 was the last in the line of Millennial Blades created during the War of MIRAI. This particular sword was modeled after Sora Hoshiko of the original SHASTALOID Project.
This model was not released to the general public due to it's capabilities. Only members of the REbellion had access to it. This model is light weight, small, and extremely powerful.
The sword model is commonly used by Olivia Utanen. though many others in the REbellion use this model too.