Takemichi reconciles his desire to change the past with the reality of his present by understanding that while he cannot change the past, he can still make a difference in the present and future. He learns to focus on the things he can control, such as protecting those he cares about and making positive choices in his current circumstances, rather than dwelling on the things he cannot change. This shift in mindset allows him to take meaningful actions in the present while still holding onto hope for a better future.