The Moon Has Risen

Talk to Kujirai Momiji: First off, you'll find Kujirai Momiji at the Inazuman Fishing Association. It's located northwest of Inazuma City, right by the southern Byakko Plain waypoint. When you chat with her, she'll tell you all about the legend of the 'Lunar Leviathan.' Apparently, it's said to grant wishes, and she believes it's real because she had a strange encounter with something like it years ago. She'll explain that she wants to find it again and needs help from her old fishing buddies, Jiawei and Nantuck. She'll mention Jiawei is in Liyue Harbor, and you'll need to ask him about Nantuck's whereabouts.

Talk to Jiawei: Next, head over to Liyue Harbor. Teleport to the lower waypoint and make your way east to the docks. You'll find Jiawei chilling on the southernmost pier. When you talk to him and mention Kujirai, he'll wish you luck but express that he's not keen on going back out into the ocean after their last harrowing experience. He'll tell you about how he and his friends, including Kujirai and Nantuck, were hunting a Lunar Leviathan when a huge storm hit, wrecking their boat and leaving them stranded. They were days without water, and Jiawei was even writing a suicide note! Just when things were dire, they saw a faint glow from a massive shape beneath the water. Desperate, they asked for safe passage home, and the shape led them back. Even though Jiawei won't join the hunt, he'll offer you some training to help you out. Completing this chat wraps up the quest and unlocks those Lunar Realm challenges!