Apparently, Disillusioned Adventurers Will Save the World, Vol. 1 (manga) by Masaki Kawakami

Veteran adventurer Nick's life is falling apart. Despite all the knowledgeand expertise he's devoted to his adventuring party, his respected leader kickedhim out, his girlfriend dumped him, and his teammates shamelessly accused him ofembezzlement. Tired, heartbroken, and looking for a drink, Nick chances upon afew kindred spirits who are jaded as he is. Together, these disillusionedadventurers form an unstoppable team out to save their bleak, depressingworld!
Binding: Paperback / softback