Additional Services' Advisor Juni:
With our class change service you can choose a different class for your character. You need to prepare for it, however
First, you need a Class Change Coupon that's sold in the Adena store section of the L-Coin Store.
Second, you have to unequip all items.
Third, you need to free up your inventory.You will need at least 30 slots.
What's more, Heroes can't change their class, so a character with this title is ineligible for the service.
Tell me once you're ready, I'll send you to the Additional Services Lab. Talk to the Researcher Hermin there to change class.