Kouhei Araki, a long-serving editor in Genbu Publishing's dictionary department, intends to step down to devote himself to caring for his sick wife. But before he leaves, he needs to find someone to take over the work on his current project—a new dictionary titled The Great Passage. No matter where he searches, though, he cannot locate a suitable candidate, since compiling a dictionary demands immense patience, time, and commitment.
Mitsuya Majime works in Genbu Publishing's sales division, but he struggles with social interactions and often fails to grasp the atmosphere around him. Despite this, he possesses a genuine passion for words, fueled by his love of reading and meticulous nature. These qualities catch Araki's attention, leading him to offer Majime a role in the dictionary editorial team. As Majime takes on his new position, he feels uncertain about his own abilities and worries about fitting in with his colleagues. Yet, amid the vast ocean of words, The Great Passage will bring them all together.