Tomohisa and Kazuna know each other since the Bambi period. Their relationship started out well. However, as time passed Kazuna felt inferior to his friend. He tries his best to act independent of Tomohisa but comes to his personal conclusion that he will always be outshined by his teammate.
In contrast, Tomohisa is not of the same opinion. For him, Kazuna is a very capable person who has his own charm and shine. He is not aware of Kazuna's conflicted feelings.