The defender arrived at St Mary's Stadium from VVV-Venlo in August 2012 and has made 60 appearances for the club in that time – scoring three goals.
In his first season at the club he was a first-team regular at centre-back, making 32 appearances as Southampton finished 14th in the Premier League.
He has played more of a peripheral role this season under Ronald Koeman, though, making eight league starts - half of those coming in the final month of 2014 alone.
Having extended his stay on the south coast, the 26-year-old has flown out to Australia to link up with Japan's Asian Cup squad ahead of their first game in the tournament against Palestine on January 12.
Defending champions Japan are expected to go a long way in the competition once again, meaning Yoshida is unlikely to feature for his club until early February.
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