The 27-year-old Gunners centre-back spoke about the defeat at the hands of the Samurai Blue, and discussed his developing partnership with talented starlet Mamadou Sakho
The 27-year-old Arsenal defender avoided injury after being involved in a collision with Franck Ribery during training last week but recovered to feature in the game, though his team were undone by a late Shinji Kagawa winner in the last few minutes of the match.
Nevertheless, Koscielny maintains that regardless of the result, Tuesday's World Cup qualifier against defending world champions Spain was always the aim.
"I was disappointed to have lost, especially like this, against a 70 metres [counterattack]. I was upset over that, compared to the opportunities we had," the former Lorient defender told L'Equipe.
"In the game, we could've gotten away with the set-pieces early. We did not. We are hurt, but even if we had won, you would have said that the most important thing was Tuesday [against Spain].
The Arsenal man was also asked to comment on his relationship with centre-back Mamadou Sakho, who could be in the line-up to face Spain with Mapou Yanga-Mbiwa suspended.
He continued: "It is fine. We train together, we know our qualities. It puts us at ease, our level rises. It did us good to play together. It is always important to have played with a partner."
Tuesday's game against Vicente del Bosque's side kicks off at 21:00 CET.