"I have always tried to support the team, but I couldn't return the trust with performances," the 27-year-old Sakai, who plays for second division German club Hamburg, told Friday's edition of newspaper Bild.
At the World Cup finals in Russia, Sakai, who made 42 appearances for Japan in six years, only featured in the 1-0 defeat to Poland in the group stages.
He joins Blue Samurai captain Makoto Hasebe, 34, and AC Milan striker Keisuke Honda, 32, who have already announced their international retirements in the last few days.
The trio stepped down in the wake of Monday's 3-2 last-minute defeat to Belgium in the last 16.
Japan crashed out after throwing away a two-goal lead in Rostov-on-Don when the Red Devils scored with the last kick of the game when Nacer Chadli finished off a counter-attack.
On Thursday, the Japanese FA confirmed that caretaker coach Akira Nishino, who only took charge 71 days before their first World Cup match, will not continue in the job.
Former Germany and USA coach Jurgen Klinsmann has been linked to the role.