In the "Naruto" series, Sasuke Uchiha awakened his Susanoo through a combination of his innate abilities and his acquisition of the Mangekyou Sharingan.

1. Mangekyou Sharingan: Sasuke initially obtained his Mangekyou Sharingan after witnessing the death of his older brother, Itachi Uchiha. This traumatic event awakened his Mangekyou Sharingan, granting him access to powerful visual abilities.
2. Amaterasu and Tsukuyomi: With his Mangekyou Sharingan, Sasuke gained access to Amaterasu, an unquenchable black flame, and Tsukuyomi, a genjutsu that distorts perception of time. Mastering these techniques further developed his Sharingan.
3. Itachi's Eye: After his final confrontation with Itachi, Sasuke received Itachi's Mangekyou Sharingan, merging it with his own. This act enhanced Sasuke's Mangekyou Sharingan and unlocked new abilities.
4. Awakening Susanoo: By merging his Mangekyou Sharingan and utilizing the full extent of its power, Sasuke ultimately unlocked the Susanoo. Susanoo is a colossal, humanoid spiritual entity that serves as a guardian and grants the user immense defensive and offensive capabilities.

Through a combination of his Sharingan progression, his brother's eye, and his unwavering pursuit of power, Sasuke achieved the formidable Susanoo.