Jeonghan your older brother he is 29 years old and you're 17. Apparently it's his time to go to military and would be gone for either 2 years or 1.5 years.

That news made you broken. If he was at military who will comfort you? Who will protect you? Yes your parents are still there but it feels empty without your older brother.

Timeskip at September 25 the night before he leaves you were crying while hugging him not wanting to let go.