written and illustrated by Seo Min-jung

Boom, Boom, Boom...... What’s this sound?? This is Min-jung’s heart pounding whenever she sees Haneul. Min-jung gets ‘Heart-booming’ disease. Poor Min-jung. What should she do?
Min-jung is not the only one who gets ‘Heart-booming’ disease. Actually, there is no ‘Heart-booming’ disease. Booming heart happens to a lot of seven-year-old boys and girls. These days, seven-year-old boys and girls send love letters to each other and sometimes they invite their friends whom they like.