Kodai Arima

is the husband of Keiko Arima and the father of Takuya Arima who is dead prior to the series.

Etymology

 * The name Kodai means "wide, broad, spacious" (広) (ko) and "big, great" (大) (dai).
 * Kodai's surname Arima means "exist" (有) (ari) and "horse" (馬) (ma).