Rukia, let me ask you something. From your experience…

““Rukia, let me ask you something. From your experience where do you think your heart is?" "um well if I had to guess I think somewhere around here isn't that right?" "If you want to be literal about it. But in my opinion it's more a state of mind. I believe its right here, not inside our bodies at all. I think a heart is created between people when they meet for the first time, a bond that's brought to life between individuals. It's an emotional connection, when you think about something or care about someone, that's where your heart is born. If you were the only person that existed in this world, your heart would have no way of forming so it just wouldn't be anywhere. There's nothing to worry about Rukia. If you believe with all of your heart that you belong here, then this is where you'll stay. If your heart is here then that's all the reason in the world you need to be here. You must never doubt that. But listen Rukia, in the fights to come, there's something I must warn you about. Something you must promise me you will never ever do. I mean this. You must never die alone. Our souls are our bodies and when we die our bodies turn to dust and become the reishi that go on to form the soul society, but where do our hearts go? We entrust our hearts to our friends. If you entrust your heart to your friends it will continue to live on inside them. That's the most important thing you'll learn from my training. Don't you dare die alone Rukia.””

— Tite Kubo