In the making of the cast, Takahashi designed multiple characters with different traits in order to deliver multiple traits that would serve as obstacles for Tsubasa to surpass. The large number of characters made Takahashi careful with their designs and he wanted to give each of them recognizable features. One of Tsubasa's early rivals, Jun Misugi, was given skills that surpassed the protagonist's. As a result, he gave Misugi a heart condition that would balance the match between their teams. When asked why Tsubasa's teams always win, Takahashi stated it was because he aims the manga to be long and thus a defeat would reduce its length. While the series was initially aimed at children, Takahashi was surprised at how, across the years, it has also attracted adults, as well as at the impact it had on Japan's football. When talking about its themes, Takahashi stated the main one is honor, which is meant to be superior than money, something which people value more.