Make sure you use pins that trigger beatdrops independently of statuses or knockback and things like that, those tend to be worse on bosses. I also had to slot a healing pin for that fight which is rarely useful in this game.
And Minamimoto is particularly rough so when all else fails just lower the difficulty
I definitely did not forget to put the 2020 GOTD Guru winner,
azuarc
in my sig!