Middlesbrough gaffer Aitor Karanka says he his happy&nbsp; Kenneth Omeruo is back to the club on a season long.<br /><br />He&nbsp; believes Omeruo&rsquo;s&nbsp; experience at the World Cup with the Super Eagles of Nigeria would help the player and his team.<br /><br />The 20-year-old defender agreed to rejoin Boro at the Riverside Stadium last month after showing like a million star at the FIFA World Cup in Brazil.<br /><br />Manager Aitor Karanka said: &ldquo;He is a very important player to us. He&rsquo;s someone I love to have with us because he&rsquo;s a player who came here from Chelsea and his mood was always perfect.<br /><br />&ldquo;He was always happy and fighting for his position. He was handed the opportunity to play in the World Cup [for Nigeria] and he is now coming back to us a better player.&rdquo;<br /><br />Middlesbrough will begin their new season with a home match against Birmingham City on Saturday.