If he wins the jgpf and the world junior title will he be the youngest to do so?
I think so. The JGPF winners were mostly 17-18 y.o. Yuzuru was the youngest till now, he was still 14 (turned 15 in one or two days) when he won his first GPF. Takahiko Kozuka, Boyang Jin and Nathan Chen were 16, the rest of the JGPF winners were older.