The defending champion in the singles was local hero Kei Nishikori , who was placed fourth this year. Alexander Peya and Bruno Soares won the doubles title last year. They did not take part in the tournament this year.
The field of participants in the individual competition consisted of 32 players, that of the doubles competition consisted of 16 pairs.
Qualification for the 2013 Rakuten Japan Open Tennis Championships took place on September 28 and 29, 2013. Four qualifying places were played, which entitle them to participate in the main draw of the tournament.
At the Rakuten Japan Open Tennis Championships 2013, the following prize money and world ranking points were paid out or credited for reaching the respective round. Players who entered the main field from qualification received the specified qualification points in addition to those for reaching the respective round. Otherwise the amounts are not to be understood as cumulative. The amounts for the double competition apply per player.