I saw a chart of linguistic distances, in which English and Japanese were placed at opposite ends.
I'm in a situation a bit similar to him, living abroad for a while, often lacking communication with local people, and talking with my family and friends every day in Japanese. That doesn't help improve your ability to speak English... :cry:
Maybe... learning English is not his priority at the moment? He might spend most of his time (except for skating) for studying, making strategies, or just gaming to refresh his mind.
But I believe someday he will concentrate to develop his English proficiency for his future career.