Farming mirrors with Spiderweb Yoshihide is too comfortable (with the 'boss' included)

First, get the red string-like gift from the general pool. (The one that prevents the killed boss and its minions from reviving) Set Yoshihide as the first character and form a 6-person party including the boss and its minions. In battle stages, use Yoshihide's evasion to wipe out everyone. Then, just proceed with Yoshihide as you like! Drawbacks Human, Heart, Nothingness