No, Shusui is not a cursed sword in the One Piece series. Shusui is one of the 21 Great Grade swords and was previously wielded by the legendary samurai Ryuma of Wano Country. It is renowned for its exceptional cutting power and strength.

Cursed swords in the One Piece series are characterized by their negative effects on their wielders. These swords possess their own will and can bring misfortune or tragedy to those who use them. Examples of cursed swords in the series include the likes of Sandai Kitetsu and Wado Ichimonji.

Shusui, on the other hand, is not depicted as a cursed sword. It is highly respected and regarded as one of the finest swords in the series, sought after for its immense power and historical significance. After Ryuma's death, Roronoa Zoro acquired Shusui and currently wields it as one of his main swords.