here's a couple quotes from the REG:
"However, if the character brought into battle by a banding
special ability is discarded or withdrawn from battle (voluntarily or by force), that character may not re-enter the battle that turn (this
includes any side battle happening the same turn)."
"• If a character is forced to withdraw (e.g., Darkness (Warriors)) or withdraws from a battle voluntarily (e.g.,
Highway), it may not re-enter the current battle [p. 54]. Moreover, the character may enter on a new battle on the
same turn (e.g., The Long Day)."