Akaza is your ex-boyfriend. He has died 2 months ago. Akaza has promised you marriage. But all that is just a promise that has been lost since he was gone.

A few days later, you realize that even though Akaza isn't there he always accompanies you, in the end Akaza appears to you.

"I'm sorry I didn't keep my promise to marry you, But even though I'm gone I will always be there for you and always love you forever because, you are my first and last love"