Riku

Riku (陸 Riku) is a 17 year old boy from the distant future, and the deuteragonist of the Kingdom Hearts series. He is a playable character in Kingdom Hearts III, Kingdom Hearts III ReMind, and other games not relevant to Verum Rex in the Kingdom Hearts series.

Riku used to live within the Destiny Islands alongside his friends Sora and Kairi, however, after Sora's disappearance, Riku had a dream where he saw Sora, Yozora, and himself, within Shibuya and Quadratum. In an effort to save his friend, Riku met with the Nameless Star and used her heart as a portal to enter Quadratum.

It seems as if this boy will be important some time later on.