Masamune is a legendary wooden sword belonging to the Saginomiya family. It was said to have the power to release the full potential of its wielder. It was crafted by the legendary craftsman, Masamune.
It was given to Hinagiku by Isumi before they entered the Tiger's Den for Butlers. Hinagiku also used it at the top of the clock tower in Hakuou against Hayate, because Hayate came very late in their scheduled meeting at the night of her birthday. It has also been used numerous times to strike Hayate and Yukiji due to their poor choice of words and actions while around Hinagiku. During Hayate's final confrontation against Athena in Athens, Hinagiku gave this sword to Hayate and he used this to fight King Midas.
In Chapter 360, it is revealed that Hinagiku still owns this sword although she now uses the Shirosakura over the Masamune as her main sword.