Shun Mitaka is the coach of the tennis club that Kyoko attends, and is the rival of Godai for her love and attention. He and Godai recognized each other as rivals from the moment they met.
Shun is notorious for being a ladies' man, and is a stud in every sense of the word, from his good looks, athleticism, and way with words, to his trademark shining white teeth, he is everything Godai is not. He had some childhood trauma concerning dogs, so he has a crippling fear of them. He comes off as a spoilt child of fortune, but is actually a really good and assiduous guy who truly loves Kyoko and is worried about letting someone unreliable have her.
He wooed Kyoko quite boldly, but ironically that approach actually strengthened Kyoko's feelings toward Godai in most cases.
Shun gets dragged into an arranged marriage affair by his scheming uncle in order to secure the Mitaka family's financial future, and is forced to court Asuna Kujo.
He continues to declare his love for Kyoko, however, and difficulties ensue.