At 3:00 in the morning, in a house in Konoha, Lee woke up. Now, normally this wouldn't be that big of an event, but it's what this story focuses on, so deal with it.
But, anyway, as Lee woke up, he sat straight up with sparkles in his eyes.
"Lee!" Gai said, appearing from the shadows.
"Gai-sensei!" Lee exclaimed, surprised at seeing his favorite (and only) sensei in his bedroom.
"Guess what day it is!" Gai asked Lee, leaning in close.
"I know what today is!" Lee shouted. "I woke up half an hour early just for it!"
"Good!" Gai remarked. "I came here to remind you, but it seems you remembered on your own!"
Lee smirked. "How could I forget International Youth Day?"
Elsewhere, Kakashi got the strangest feeling that today would be a great day to sleep in.