A while back, when the game came out, I came across a forum topic on Gamefaqs that contained a lot of useful information to help you master your class. I thought it would be nice to share its information with you. It should help you find all the different NPCs for each class who can give you more quests to rank up. Plus, it will tell you where to find the class shop as well.
Paladin - Life Shop: Mt. Snowpeak Summit
Master Mustang: Castele Square - Paladins' Hold [Invite to party at God]
Tad: Castele Square - Paladins' Hold
Roslyn: South Castele - Stables [Invite to party at Master]
Isobel: Castele Square - Outside Paladins' Hold [Invite to party at Expert]
Porthos: Castele Shopping District (Day), The Crown (Night) [Invite to party at Adept]
Mr Apfel: Castele Aritans' District - Appleseed Cafe
Dragonslayer: West Grassy Plains [Invite to party at Hero]
Mercenary - Life Shop: Al Maajik Spelltown
Master Cervantes: Castele Shopping District - The Crown [Invite to party at God]
Bard: Castele Shopping District - The Crown
Jude: South Castelle (Day), Castele Shopping District (Night) [Invite to party at Adept]
Gustaf: East Grassy Planes - Near Mt. Snowpeak Entrance
Santos: Port Puerto Palace Way (Day), Port Puerto Palace (Night)
Melusine: Cacto Cave - Melusine's House [Invite to party at Master]
Miguel: Al Maajik Spelltown - Miguel's House [Invite to party at Hero]
Hunter - Life Shop: West Grassy Plains - Traveller's Respite
Master Fern: East Castele - Outside Fern's House (Day), Fern's House (Night) [Invite to party at God]
Lucky: East Castele - Outside Fern's House (Day), Fern's House (Night) [Invite to party at Adept?]
Huntin' Pete: South Castele - Sheep Pen [Invite to party at Adept?]
Granny Cotton: South Castele - Sheep Pen
Fletcher: West Grassy Plains - Traveller's Respite [Invite to party at Hero]
Roy: Port Puerto Palace Way
Boyd: Al Maajik Outskirts
Magician - Life Shop: Al Maajik Spelltown - Esmerelda's Academy of Magic
Master Jinx: East Castele - Hazel's House [Invite to party at God]
Hazel: East Castele - Outside Hazel's House (Day), Hazel's House (Night) [Invite to party at Master]
Nox: East Castele - Castele Forest [Invite to party at Adept]
Fabbie: Port Puerto Palace Way - Park [Invite to Party at Expert]
Esmerelda: Al Maajik Spelltown - Esmerelda's Academy of Magic (Day), Outside Academy (Night)
Colin: Ancient Ruins Path [Invite to party at Hero]
Skybie: Levitania - Plushling Camp
Miner - Life Shop: Mt. Snowpeak Summit - Well
Master Duglas: East Castele - Castele Mine [Invite to party at God]
Molan: East Castele - Castele Mine
Daniel: East Castele - Castele Mine (Day), Just outside Castele Mine (Night)
Marie: Castele Artisans' District (Day), Duglas' House (Night)
Moleo: Port Puerto Beach District - Near South Beach
Rocque: Al Maajik Outskirts - Near Desert Entrance (Day), The Watering Hole (Night) [Invite to party at Adept?]
Angela: Al Maajik Sandtown - Near East Shops (Day), The Watering Hole (Night) [Invite to party at Master]
Molina: Al Maajik Outskirts
Woodcutter - Life Shop: Elderwood Village
Master Heyho: East Castele - Heyho's House [Invite to party at God]
Monika: East Castele - Outside Heyho's House (Day), Heyho's House (Night) [Invite to party at Adept]
Bracken: East Castele - Castele Forest
Forrest: East Castele - Castele Forest
Orlando: Port Puerto Beach District - Near Turtle Stall (Day), Port Puerto Marina (Night) [Invite to party at Expert]
Timber: Port Puerto Beach District - Near Lighthouse
Cedar: Al Maajik Library of Magic (Day), Al Maajik Outskirts - Near Save Point (Night)
Leafelet: Al Maajik Outskirts - West of Save Point
Elmie: Elderwood Village [Invite to party at Master?]
Angler - Life Shop: Port Puerto Palace Way - Angler's Association
Master Fisherman Sage: West Castele - Outside Isaac's House [Invite to party at God]
Trout: West Castele - Outside Isaac's House
Isaac: West Castele (Day), Outside Isaac's House (Night) [Invite to party at Adept]
Guppy: Port Puerto Beach District (Day), Palace Way - Angler's Association (Night)
Marina: Port Puerto Palace Way - Angler's Association (Day), Beach District (Night) [Invite to party at Expert]
Seaburry: Port Puerto Beach District
Tabita: Al Maajik Spell Town - The Spice Rack
Anchovy: Al Maajik Outskirts
Cook - Life Shop: Castele Shopping Disctrict - Alfredo's Bistro
Master Alfredo: Castele Shopping Disctrict - Alfredo's Bistro [Invite to party at God]
Flapjack: Castele Shopping Disctrict - Alfredo's Bistro
Sizzle: Castele Shopping Disctrict - Alfredo's Bistro (Day), West Castele - Near Chicken's (Night) [Invite to party at Adept?]
Allan: Castele Shopping District - Near Shops (Day), Castele Aritans' District - Appleseed Cafe (Night) [Invite to party at Adept]
Pedro: Port Puerto Palace Way - Cocina Rica (Day), Port Puerto Marina - Pirate Ship (Night)
Mary Anne: Tortuga Archipelago - Alejandro's Beach Hut
Jill: Al Maajik Spell Town - The Spice Rack [Invite to party at Adept]
Blacksmith - Life Shop: Mt. Snowpeak - Lava Cave
Master Vulcan: Castele Artisans' District - Royal Castele Workshop [Invite to party at God]
Fyra: Castele Artisans' District - Royal Castele Workshop
Magmia: Castele Artisans' District (Day), Steele's House (Night) [Invite to party at Adept]
Ignatius: Castele Square - Paladins' Hold (Day), Castele Artisans' District (Night) [Invite to party at Expert]
Durandal: Mt. Snowpeak - Waterfall Cave
Ironsmith: Mt. Snowpeak - Lava Cave (Day)
Sebastan: Port Puerto Marina - Outside Pirate Ship (Day), Castele Shopping Disctrict - Alfredo's Bistro (Night)
Carpenter - Life Shop: Elderwood Village
Master Woody: Castele Artisans' District - Royal Castele Workshop [Invite to party at God]
Sawyer: Castele Artisans' District - Royal Castele Workshop
Cherry: Castele Artisans' Distric - Near Well (Day), Woody's House (Night) [Invite to party at Adept]
Beavy: Castele Artisans' Distric - Near Well
Beavo: Castele Artisans' Distric - Near Well (Day), Near Pet Shop (Night)
Decker: Port Puerto Marina - Leftmost Ship [Invite to party at Expert]
Marimo: Elderwood Village
Tailor - Life Shop: Port Puerto Palace Way - Madam Purl's House (Parrot)
Master Madam Purl: Castele Artisans' District - Royal Castele Workshop [Invite to party at God]
Spoolie: Castele Artisans' District - Royal Castele Workshop
Taylor: West Castele - Near Church (Day), Castele Square - Fashion Boutique (Night)[Invite to party at Expert?]
Zippy: Castele Square - Outside Fashion Boutique (Day), Fashion Boutique (Night)
Chic: Port Puerto Palace Way - Madam Purl's House (Day), Fashion Boutique (Night) [Invite to Party at Master?]
Lyra: Port Puerto Palace Way - Fashion Boutique
Bobbin: Al Maajik Sandtown - Bazaar Workshop
Alchemist - Life Shop: Al Maajik Sandtown - Prof. Snooze's Laboratory
Master Flamel: Castele Square - Royal Castele Library [Invite to party at God]
Beaker: Castele Square - Royal Castele Library
Fizz: Castele Artisans' District - Near Shops (Day), Castele Square - Royal Castele Library (Night) [Invite to part at Expert?]
Rupert: Castele Square - Outside General Goods (Day), Near Small Pier (Night)
Petri: Port Puerto Marina - Outside Crankshaft's Workshop (Day), Crankshaft's Workshop (Night) [Invite to party at Master?]
Prof. Snooze: Al Maajik Sandtown - Prof. Snooze's Laboratory
Genieus: Al Maajik Sandtown - Prof. Snooze's Laboratory
It might not be 100% accurate, specially the information regarding when you can invite someone in your party, but it will still give you a list of where to find which NPC for each class. All the credits go to CamulaHikari from Gamefaqs.
Paladin - Life Shop: Mt. Snowpeak Summit
Master Mustang: Castele Square - Paladins' Hold [Invite to party at God]
Tad: Castele Square - Paladins' Hold
Roslyn: South Castele - Stables [Invite to party at Master]
Isobel: Castele Square - Outside Paladins' Hold [Invite to party at Expert]
Porthos: Castele Shopping District (Day), The Crown (Night) [Invite to party at Adept]
Mr Apfel: Castele Aritans' District - Appleseed Cafe
Dragonslayer: West Grassy Plains [Invite to party at Hero]
Mercenary - Life Shop: Al Maajik Spelltown
Master Cervantes: Castele Shopping District - The Crown [Invite to party at God]
Bard: Castele Shopping District - The Crown
Jude: South Castelle (Day), Castele Shopping District (Night) [Invite to party at Adept]
Gustaf: East Grassy Planes - Near Mt. Snowpeak Entrance
Santos: Port Puerto Palace Way (Day), Port Puerto Palace (Night)
Melusine: Cacto Cave - Melusine's House [Invite to party at Master]
Miguel: Al Maajik Spelltown - Miguel's House [Invite to party at Hero]
Hunter - Life Shop: West Grassy Plains - Traveller's Respite
Master Fern: East Castele - Outside Fern's House (Day), Fern's House (Night) [Invite to party at God]
Lucky: East Castele - Outside Fern's House (Day), Fern's House (Night) [Invite to party at Adept?]
Huntin' Pete: South Castele - Sheep Pen [Invite to party at Adept?]
Granny Cotton: South Castele - Sheep Pen
Fletcher: West Grassy Plains - Traveller's Respite [Invite to party at Hero]
Roy: Port Puerto Palace Way
Boyd: Al Maajik Outskirts
Magician - Life Shop: Al Maajik Spelltown - Esmerelda's Academy of Magic
Master Jinx: East Castele - Hazel's House [Invite to party at God]
Hazel: East Castele - Outside Hazel's House (Day), Hazel's House (Night) [Invite to party at Master]
Nox: East Castele - Castele Forest [Invite to party at Adept]
Fabbie: Port Puerto Palace Way - Park [Invite to Party at Expert]
Esmerelda: Al Maajik Spelltown - Esmerelda's Academy of Magic (Day), Outside Academy (Night)
Colin: Ancient Ruins Path [Invite to party at Hero]
Skybie: Levitania - Plushling Camp
Miner - Life Shop: Mt. Snowpeak Summit - Well
Master Duglas: East Castele - Castele Mine [Invite to party at God]
Molan: East Castele - Castele Mine
Daniel: East Castele - Castele Mine (Day), Just outside Castele Mine (Night)
Marie: Castele Artisans' District (Day), Duglas' House (Night)
Moleo: Port Puerto Beach District - Near South Beach
Rocque: Al Maajik Outskirts - Near Desert Entrance (Day), The Watering Hole (Night) [Invite to party at Adept?]
Angela: Al Maajik Sandtown - Near East Shops (Day), The Watering Hole (Night) [Invite to party at Master]
Molina: Al Maajik Outskirts
Woodcutter - Life Shop: Elderwood Village
Master Heyho: East Castele - Heyho's House [Invite to party at God]
Monika: East Castele - Outside Heyho's House (Day), Heyho's House (Night) [Invite to party at Adept]
Bracken: East Castele - Castele Forest
Forrest: East Castele - Castele Forest
Orlando: Port Puerto Beach District - Near Turtle Stall (Day), Port Puerto Marina (Night) [Invite to party at Expert]
Timber: Port Puerto Beach District - Near Lighthouse
Cedar: Al Maajik Library of Magic (Day), Al Maajik Outskirts - Near Save Point (Night)
Leafelet: Al Maajik Outskirts - West of Save Point
Elmie: Elderwood Village [Invite to party at Master?]
Angler - Life Shop: Port Puerto Palace Way - Angler's Association
Master Fisherman Sage: West Castele - Outside Isaac's House [Invite to party at God]
Trout: West Castele - Outside Isaac's House
Isaac: West Castele (Day), Outside Isaac's House (Night) [Invite to party at Adept]
Guppy: Port Puerto Beach District (Day), Palace Way - Angler's Association (Night)
Marina: Port Puerto Palace Way - Angler's Association (Day), Beach District (Night) [Invite to party at Expert]
Seaburry: Port Puerto Beach District
Tabita: Al Maajik Spell Town - The Spice Rack
Anchovy: Al Maajik Outskirts
Cook - Life Shop: Castele Shopping Disctrict - Alfredo's Bistro
Master Alfredo: Castele Shopping Disctrict - Alfredo's Bistro [Invite to party at God]
Flapjack: Castele Shopping Disctrict - Alfredo's Bistro
Sizzle: Castele Shopping Disctrict - Alfredo's Bistro (Day), West Castele - Near Chicken's (Night) [Invite to party at Adept?]
Allan: Castele Shopping District - Near Shops (Day), Castele Aritans' District - Appleseed Cafe (Night) [Invite to party at Adept]
Pedro: Port Puerto Palace Way - Cocina Rica (Day), Port Puerto Marina - Pirate Ship (Night)
Mary Anne: Tortuga Archipelago - Alejandro's Beach Hut
Jill: Al Maajik Spell Town - The Spice Rack [Invite to party at Adept]
Blacksmith - Life Shop: Mt. Snowpeak - Lava Cave
Master Vulcan: Castele Artisans' District - Royal Castele Workshop [Invite to party at God]
Fyra: Castele Artisans' District - Royal Castele Workshop
Magmia: Castele Artisans' District (Day), Steele's House (Night) [Invite to party at Adept]
Ignatius: Castele Square - Paladins' Hold (Day), Castele Artisans' District (Night) [Invite to party at Expert]
Durandal: Mt. Snowpeak - Waterfall Cave
Ironsmith: Mt. Snowpeak - Lava Cave (Day)
Sebastan: Port Puerto Marina - Outside Pirate Ship (Day), Castele Shopping Disctrict - Alfredo's Bistro (Night)
Carpenter - Life Shop: Elderwood Village
Master Woody: Castele Artisans' District - Royal Castele Workshop [Invite to party at God]
Sawyer: Castele Artisans' District - Royal Castele Workshop
Cherry: Castele Artisans' Distric - Near Well (Day), Woody's House (Night) [Invite to party at Adept]
Beavy: Castele Artisans' Distric - Near Well
Beavo: Castele Artisans' Distric - Near Well (Day), Near Pet Shop (Night)
Decker: Port Puerto Marina - Leftmost Ship [Invite to party at Expert]
Marimo: Elderwood Village
Tailor - Life Shop: Port Puerto Palace Way - Madam Purl's House (Parrot)
Master Madam Purl: Castele Artisans' District - Royal Castele Workshop [Invite to party at God]
Spoolie: Castele Artisans' District - Royal Castele Workshop
Taylor: West Castele - Near Church (Day), Castele Square - Fashion Boutique (Night)[Invite to party at Expert?]
Zippy: Castele Square - Outside Fashion Boutique (Day), Fashion Boutique (Night)
Chic: Port Puerto Palace Way - Madam Purl's House (Day), Fashion Boutique (Night) [Invite to Party at Master?]
Lyra: Port Puerto Palace Way - Fashion Boutique
Bobbin: Al Maajik Sandtown - Bazaar Workshop
Alchemist - Life Shop: Al Maajik Sandtown - Prof. Snooze's Laboratory
Master Flamel: Castele Square - Royal Castele Library [Invite to party at God]
Beaker: Castele Square - Royal Castele Library
Fizz: Castele Artisans' District - Near Shops (Day), Castele Square - Royal Castele Library (Night) [Invite to part at Expert?]
Rupert: Castele Square - Outside General Goods (Day), Near Small Pier (Night)
Petri: Port Puerto Marina - Outside Crankshaft's Workshop (Day), Crankshaft's Workshop (Night) [Invite to party at Master?]
Prof. Snooze: Al Maajik Sandtown - Prof. Snooze's Laboratory
Genieus: Al Maajik Sandtown - Prof. Snooze's Laboratory
It might not be 100% accurate, specially the information regarding when you can invite someone in your party, but it will still give you a list of where to find which NPC for each class. All the credits go to CamulaHikari from Gamefaqs.
