sunshine-force:

According to the interviews with anime director Akiyama and Kamakura:

• Taiyou’s position in GO is that of Ichinose and Fideo in the original Inazuma Eleven.
• Taiyou is not affected by Fifth Sector’s commands and plays soccer freely. Because of this, he is Tenma’s first “true” rival.
• Rather than a rival, Taiyou is presented to be Tenma’s counterpart, a person who loves soccer just as much as Tenma does.
• Seitei supports Taiyou and Arakumo, because Arakumo is one of the teams he raised for the purpose of “free soccer” (the meaning of this will be revealed later in the anime)
• Senguuji is like Kageyama, he loves soccer, but his love for soccer is distorted.
• Arakumo Gakuen only obeys fifth sector’s commands because Taiyou is not around. When Taiyou returns, the team plays for free soccer. That is the true Arakumo Eleven.
• Arakumo Eleven’s main spirit is not in winning, but in “protecting Taiyou”. They are a very supportive and gentle-hearted team.
• Sata Tosamaru is Taiyou’s confidant and close friend. (kind of like Sakuma to Kidou)

Terasaki Yuka’s Interview:

• Taiyou is a mysterious boy who stumbled abruptly into Tenma’s life. They are similar in that they’re both so passionate about soccer. If it had been Tenma who was ill, he would have acted the same as Taiyou. But Taiyou is a more sensitive boy than Tenma. He’s probably popular with girls (lol). 
• Terasaki thought Tenma had hoped that he could play soccer together with Taiyou. That’s why Tenma was so shocked when Fuyuka told him about Taiyou’s illness.
• Terasaki nearly cried after recording for the last part of the Arakumo match (where Taiyou laid on the ground…). But she says Tenma absolutely cannot cry because what he said would sound like a lie. And Tenma has to be strong in this scene.
• Tenma could become more assertive of himself in the Arakumo match because Taiyou’s challenge to him is real. It’s not a match against teams controlled by fifth sector, it’s a real match against people who love soccer.