Zenjirou Tsurugi

Zenjirou Tsurugi is Taiki's classmate and self-proclaimed “eternal rival.” A kendo practitioner said to be the strongest middle-school swordsman in Kōtō, he starts following Taiki after losing to the amateur in a tournament to settle the score. Because his parents work with machinery, Zenjirou is also highly knowledgeable about machines and can repair Ballistamon.