In the volcanic continent of Onsen, few of the people collect the crystal fragments from within the ancient ruins (since the job classes were invented a long time ago). However, the king of Onsen decreed that anyone who has chosen a job class must train under a master. It is entirely possible for anyone to use the crystal fragment to copy the job class, as long as the master of the job class allows it (example: Cicero created the scrubber job class by using the crystal fragment as permitted by Octavius before the story started). Some of the job classes within the crystal fragments are found within the ruins near Mount Vesu were once used by its inhabitants, before the volcano erupted and buried the town under ash.

Now, researchers from the castle have excavated the crystal fragments and refurbish the job classes to good use. Since the crystal fragments originated from the fire crystal, researchers has to be very careful when refurbishing the job class and/or inventing a job class. One wrong move and the energy within would've released, thus rendering it useless (but it is possible to restore the crystal fragment by exposing it to the fire crystals energy).

The job classes (So far) includes:

Winemaker- experts at making wine can make allies or enemies go berserk. Their sober ability can remove the berserk status from their allies, not to mention combining possible ingredients to create wine that can do status ailments. Male winemakers are dressed in toga with grape vines that decorate it (with grapes on the vines), sandals, and a wreath made from grape vines and grapes (note: the male attire of the winemaker is based on the Bacchus painting). Female winemakers wore dresses with grape vines that decorate it, sandals, and a wreath made from grape vines and grapes.

Cupid- a sub class of the ranger, Cupids can enchant their arrows that can either inflict the love status ailment (a type of status ailment that makes the target fall in love with a specific person and mimicking their moves) or inflict the hate status ailment (think of it as the charm spell from later final fantasy games, but only making the target under the hate status to attack the specific person). Heartbreak deals damage to enemies under the love status while reconcile deals damage to enemies under the hate status, not only that, but the Cupid has the passive ability to resist charm. Male Cupids are dressed in a toga that is decorated with hearts, sandals, fake wings, and gold circlets with a heart on it (since the outfit is based on the classical depiction of cupid/eros). Female Cupids wore red dresses with heart patterns, sandals, gold bracelets, and a circlet made up of hearts.

Gladiator- an ancient melee job class that deals heavy damage by equipping a wide range of weaponry, except for rods and staves. Their melee abilities can target all enemies, but they can use the enemies weak point to their advantage. Both the male and female gladiators wore armor that is reminiscent to ancient Roman gladiators, but with a theme of the summoned monsters.

Oracle- soothsayers who can predict natural disasters and direct them at foes, their main abilities includes: condemn (sentence a target to the effects of random spells) and predict (foretell cataclysm that can damage foes). Male and female oracles are dressed in ornate robes and gold circlets with large crystals at the center, in which it makes their headgear look like an eye.

It makes sense that the culture of Onsen resembled that of Italy, including ruins that are based on ancient Roman architecture and Mount Vesu is obviously a short name for "Vesuvius". The job classes are based on renaissance art, and everyday Roman jobs. Fun fact: the scrubber job class originates from Onsen due to the continent's hot springs, and it's been around since one thousand years ago.