Takeru

Takeru is the son of Susa and Kushinada. In The Lost Age, Kushinada mentions that her and Susa's son will be called Takeru and will rush to Felix' help when needed.

In Dark Dawn
Following a premonition from his sister, Himi, Takeru leaves Yamata in order to help Isaac. This occurs prior to player's arrival in Yamata, and thus, he is not actually seen in-game in person, but is mentioned in conversation.