I finally obtain Jiji, when I was around level 72 by smithing 550/550/550/550 using Fuji ema. YAY! Fuji ema does increase the probability obtaining rare swords XD
I was smithing for Kogitsunemaru but got Jiji instead aha!
Btw, this is the recipe board for successful jiji smithing record: Munechika recipe board
Meanwhile for the whole board recipe enlisted here: Recipe board
Hakata Toushirou is able to be smith during this limited time, so by all means if you haven’t got him. Good luck obtaining him in the event.