To have all your clothes destroyed by an enemy you must lose to an enemy Drive or Super Drive attack while your character is in the underwear.
Go to the last level with your most leveled up character. This is a duel with overpowered Koharu. She loves to do a Drive attacks, which is exactly what you need.
Battle with her until you have 1 pot of energy to perform a Drive, but not go into a Drive yet.
From that moment, let her beat you until two conditions are met:
1. Your character has only underwear left.
2. You have sufficiently small amount of HP, about 1/6 of the HP bar.
If there's a lot of clothing left but the HP is almost depleted, perform a Drive, it'll fully heal you and it should be enough to successfully finish this.
After the character is only in underwear and low HP, evade Koharu at all costs until she starts performing the Drive attack or Super Drive (even better). At that moment, just dash into the damage animation area. If your character survives, wait again and repeat that when the another chance appears.