The Late Riser side quest in Octopath Traveler 2 requires you to put a fisherman to sleep so he can wake up at nighttime and go fishing. He won’t go to sleep normally so you’ll have to knock him out. But doing so is the tricky bit.
This guide helps you locate the quest’s area and tips on putting the fisherman to sleep.
Sleepy Fisherman Location in Octopath Traveler 2

You will find the sleepy fisherman in “The Late Riser” side quest at Tropu’hopu, Toho’haha region.
How to Complete the Late Riser Quest in Octopath Traveler 2?

The only way to complete the quest is by challenging the Sleepy Fisherman to a dual when you first spot him and knocking him out in front of his boss. You can either use Throne, Castti, Hikari, and Ochette to put him to sleep. However, some ways use different methods.
Hikari
The best way to complete this quest is to use Hikari and Challenge the Sleepy Fisherman right on the spot. When challenged, you can use Hikari’s sword to break the fisherman’s 2 shields and defeat him.
Ochette
Another way is to use Ochette and provoke the fisherman. You can also use Akala in this battle, as he is vulnerable to bow and sword damage.
Castti
The next method involves using Castti to soothe the sleepy fisherman and put him to sleep. However, note that it will require some hard and expensive items to come by for Castti.
Throne
You can also use Throne to ambush the fisherman at night, but this will only partly work. The Master Fisherman will thank you for putting him to sleep, but he will not wake up when the time is right.
Rewards of The Late Riser Quest in Octopath Travel 2

Once you put the fisherman to sleep, the Master Fisherman will reward you with 4,800 leaves and a Slippery Nut(M). You will also get to learn his Buttom’s Up skill.