Sigh of the Shadow is one of the 42 Shrine Quests integrated into The Legend of Zelda: Breath of The Wild storyline. Upon successful completion of this quest, it reveals the Sasa Kai Shrine hidden in the Gerudo Highlands region.
Location
At the top of Gerudo Tower, located to the North of Gerudo Town.
Upon entering the Gerudo Region, ascend to the summit of Gerudo Tower. The most efficient approach is to climb to a higher area from the Highlands and then employ the glider to descend to the tower’s peak.
After reaching the tower and activating it, engage in a conversation with a character named Kass, whom you will find atop the tower. He will be playing his accordion and singing a song taught to him by his mentor. The song goes: “As light shines from the northwest skies, From the tower’s shadow an arrow flies. Pierce heaven’s light to reveal the prize.”
After listening to the song, look to the south of the tower, where Kass is gazing. You will observe a platform on the ground. Utilizing the Paraglider, glide down to the platform.
Once atop the platform, await the clock to strike 3:00 PM. After that, draw your bow, fire an arrow at the sun. You’ll know it’s the right moment to release the arrow when the platform emits a sound, and the sun’s brightness diminishes.
Upon completing this, the Sasa Kai Shrine will appear nearby.