Instead of using Fuguki, you could replace him with Rin or New Year Hashirama if you have them.

New Year Hashirama's mystery is good counter against immune ninjas, usable in round 1, and reduces your opponent's max chara to 60. His chase will hit knocked down units and increase their mystery usage by 20 chara, comboing with his mystery's chara reduction to the opponent's team. His passive 1 is pretty good with the small heal, removal of all debuffs on one ally, and one additional chase.

Rin's mystery is okay, you can pretty much spam it every round thanks to her chase 1. She has a good heal that can cancel all debuffs on your two lowest ally ninjas. Her passive 1 is really good with the damage reduction of 90% on the first mystery hits on each ally ninja, her 25% healing effects will help Scarlet Blaze's Ninjutsu Urge.