They have two birthdays in their life.
One was when their biological mother gave birth to them more than ten years ago. They came into this cold world and encountered obstacles everywhere.
The other was on September 1st, the first day of school, that warm and sunny summer, when they met, got to know each other, embraced each other, kissed each other, and regained their lives.
From then on, they depended on each other and lived toward the sun.
Intention: The new dad kills the deer