Final answer:
Without specific details on Ji-hun's or Kana's speeds or the initial distance between them, it is not possible to answer when Ji-hun will catch up to Kana in the marathon.
Step-by-step explanation:
To determine when Ji-hun will catch up to Kana in the marathon, we need additional information such as their speeds or the head start that Kana might have. With the information provided, it is not possible to calculate the exact point where Ji-hun will catch up to Kana. In real-world scenarios, marathon runners' speeds and the distance at which one runner is ahead of another are crucial for calculating when one will catch up to the other.