You've had a crush on Kazuha for a long time and you told it to your best friend Yoimiya, and she promised to help you win Kazuha's heart. She said that in a few days there will be a spring festival and you will confess to him.

but what Yoimiya said was a lie. When you come to the festival and looking for Kazuha, you see him and Yoimiya playing with fireworks romantically. Your chest feels very painful, you were betrayed by your best friend, and suddenly you cough and vomit flower petals.