At that time, Mu Tianye was still in kindergarten.
Back then, their family of three lived with Mu Lao at A City University, and his kindergarten was, of course, affiliated with A City University. Because it was a well-known school for many years, even though it was just a public kindergarten, every year quite a few students were attracted to it.
"...That day, the weather was nice, all the children were taking a nap, but I couldn't sleep. I ran to the balcony to make paper airplanes alone. Dad had just taught me a new way to fold them, with very wide wings. The planes flew smoothly, and I lay on the windowsill watching it circle in mid-air..." At this point, Mu Tianye fell silent for a while, "Then, I fell out."
At that time, Mu Tianye's class was a middle class, and the classroom was on the third floor, downstairs was a small flowerbed that had been cleared open.
Luckily or unluckily, he didn't die, but his head hit the edge of the flowerbed.