He has lost his memory.
He lost most of his memory after his 16th birthday
Later, he entered the infinite space in order to restore his memory.
His memory was even more damaged.
He only remembered their purpose
Just to get back the past, all the glory.
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"Don't worry, I will never forget you."
"Please tell me, who am I?"
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"You can't die. Go quickly. Remember, this is a prosperous age and it will last forever!"
"Sir, everything is fine in this world. The mountains and rivers are still there, the old friends are still there, the sea is clear and the rivers are flowing. It can be called a prosperous age."
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"Teacher, what are you waiting for?"
"Waiting for a future encounter"
Intention: Don't be idle and feel uncomfortable