Kotarou's nickname is "Kotarou the Runner".  He's a master of defensive battles, and minimizing losses when things turn bad.  His quiet, unassuming nature and the way he fights make him less likely to stand out than his other friends.  However, if he was put up against a real foe, someone who he couldn't beat unless he gave up on running, you might just learn his true name...
You know what the enemy 
calls the way he fights?
هل تعرفون بماذا يصف العدوّ طريقة قتاله؟
Pero ¿saben cómo lo llama
el enemigo por eso?
Sabem como os inimigos o 
chamam com esse jeito de lutar?