Bring a medium pot of water to a rolling boil. Add the tapioca pearls and cook at a gentle boil for 25-30 minutes until the pearls are fully translucent with no white dot in the center. Stir occasionally to prevent sticking.
Note: if the white dot is not disappearing, try adding more water to the pot. Sometimes, if there is not enough water, they don't go translucent.
Rinse the tapioca with cold water, then drain and set aside.
Peel all the mangoes and set one aside. Chop 3 of them and add to a large bowl. Blend the remaining mango with the coconut milk, milk, and sweetened condensed milk until smooth.
Pour the blended mango into the bowl of chopped mangoes. Stir in the drained tapioca. Stir in pineapple juice, if using.
Serve immediately or chill for one hour if you like it cold.
Nutrition information is calculated using an ingredient database and should be considered an estimate.