(This isn't canon to the plot, I just thought I'd show how strong Kai's and Akira's bond and relationship as siblings is.)

"If I could rewind and change my mind and do it all again~" Akira sang softly, "With all the answers ahead of me and knew how it would all end~ Could I make the right choice, like before I knew~ That our destinies were tied to each other, it was me or you~ One not two~"

Kai then walked down the hallway, stopping upon hearing his sister singing. He curiously peaked into the room as Akira continued to sing.

"Kai, it was you and I, Side by side since our parents had died back then~ We had no one else, just ourselves, No one was left in our defense~" Akira sang softly, smiling sadly to herself as she sang.
"We had each other, there was no better brother, You were my best friend... Until it was my end~"

Kai froze at those words, but he tried not to start to assume things right away.

"We walked through hell together~ We weathered every weather~ The stormy wind carried along my weary withered feathers~!
Would I rewind and change my mind and leave it all behind?...~" Akira asked herself before answering her own question as she continues to sing. "Not on your life~"

Kai simply continues to listened before slowly walking into the room.

"We came into the world in a whirl split by our blood and our loyalties~ We walked upon a line you and I, plagued by floods of brutality~ Two lovers didn't know~ That their choices would shape us so~ That neither side was home... Or we'd go through hell alone~... If they could rewind and change their minds and do it all again~
I'd doubt they'd go without each other either now or then~
If we could ask about our mother's past and why she stayed with Dad...She would pull us close, nose to nose, and this is what she'd say~!If I could rewind and change my mind and do it all again, again, again, again~ With all the answers ahead of me and knew how it would all end~ Would I make the same choice like before I knew~ That our destinies were tied to each other~ It was me and you~ One not two~ One not two~ One not two~ One not two~ One not two~" She sang softly before noticing Kai.

"I can feel my heartbeat racing
I don't know if this is my place and yet
I feel inside I must die for you to survive my brother I~" Akira continued to sing, holding eye contact with her brother. "I love you so, more than you know~ It's time to go but you won't ever be alone..~"

Kai felt his blood run cold at those words. Time to go...?

Akira continued. "If I could rewind and change my mind and do it all again~ With all the answers ahead of me and knew how it would all end~ I know I'd make the same choice and now I know it's true~! That our destinies were tied, I would die for you...~" Akira then outstretched her wings and started to fly, she looked like an Angel. "Me or you~ One not two~ One not two~ Me or you~ One not two~ One not two~ Me or you~ Me or you~ One not two~" She repeated before looking down at Kai.

"I would die for you~..." She finished.