Yuma and Tori are best friends, though there's a few bumps here and there, nothing can separate them. Then, one day, fate decided to pull them closer together, ending up with the two being closer than just friends... Skyshipping (Yuma X Tori)

Skyshipping, hints of HolyIce and Determination. After the Ceremonial Battle, Astral entrusted Yuma with the Key and the Numbers, and departs for the Astral World. Yuma is melancholy for parting by his friend after so many adventures. But Kotori can't bear seeing him like that, and decides to finally reveal him something that, hopefully, will cheer him. Based on current spoilers.