How can you get the magus sisters in Final Fantasy x?

To obtain the Magus Sisters in Final Fantasy X, you need to complete the side quest involving the celestial weapon "Nirvana" for Yuna. First, collect all the necessary items to unlock the "Sunken Cave" in the Calm Lands, where you can find the Magus Sisters. After defeating them in battle, you will receive their aeon. Be prepared, as this encounter can be challenging!