Ki-ni shinai-de.

                     (translation: Never mind. ／　That's all right.)

Ex.

      1. A : I  can't come to your birthday party this weekend. I'm so sorry.

          B : Ki-ni shinai-de( Never mind ). I know you've been super busy

               this week.  

       2.  A: It looks like I was supposed to bring something like snacks.  

           B : Ki-ni shinai-de ( That's all right ). We have tons already.