The quest is unlocked after completing the All Hyrule, United scenario.
"The winners of the sand-seal race will have the special honor of a private meeting with Riju! The young chief wants to bring some fruit as a small gift for the victorious vai and her sand seal."
"You learned much from listening to the vai talk about her experiences. In return for the gift, she agreed to join Riju and Patricia's future training sessions!"
- Riju: Bonus Combo