The setting of the heroine is purely fictitious, Yoshimitsu does not have such a vibrating sword.
Sakurami Toshiro, the first sword made by Yoshimitsu Awataguchi. When forged, the blade has a cherry blossom-like pattern, hence its name. It was kept by Yoshimitsu because of its rare hamon, but it was stolen after Yoshimitsu's death. It circulated around and was collected by Date Masako. Then he was sacrificed to China by accident, and happened to take form in China, which was full of spiritual power at that time.
As a result, Sakurami was abducted by Fox Nosuke to the legendary Dark Honmaru.
Cp has been confirmed to be a shock in one issue
Concept: Deep love between brother and sister (?)