Beware the Kamiki Brothers! 4

It's surprising, but Iroha and Souichirou just can't seem to see eye-to-eye. Meanwhile, the battle for Iroha's heart rages on between Souichirou and the silver-tongued prince, Kido! On the final day of their field trip, something will add stoke the fire of Souichirou's affections... What could it possibly be? Who will win this fight?