Zenjirou Tsurugi 剣ゼンジロウ

Taiki's classmate who calls himself his "eternal rival". He practices kendo and is said to be the strongest middle school kenshi in Kōtō. After being defeated by the amateur Taiki during a certain kendo tournament, he has been following him around in order to set the score straight. His parents are businesspeople in the field of machinery and because of that, he has the unique talent of being very knowledgeable about machines, and so he also does things such as repairing Ballistamon.