Nino's surname

[asweetsymphony.livejournal.com]

From what I understood, Nino's parents split up a long time ago. Does anyone know if Ninomiya is his mothers maiden surname or his Dad's?

It seems that the Japanese law requires the child to change its surname once their parents divorce to its Mother's maiden name. For example: Takizawa Hideaki and Yamashita Tomohisa use their mothers maiden name. However, Nino didn't officially state this like Takki and Yamapi.

Anyways, I'm just curious and have been wondering this whenever Nino talks about his Father.

Thank you in advance!