To complete or at least increase your world exploration progress in Inazuma, you need to complete world quests, and one of them is the “Fertilizer… Salesperson?”. This world quest will only be available to you after you have completed Sanggonomiya Kokomi’s story quest Dracaena Somnolenta chapter.
Once the prerequisite quest is done, go to Bourou Village in Watatsumi Island, and an exclamation mark—indicating an available quest—can be found on your map. This quest mark points to a man named Iwata in a crop garden.
Steps in Completing the Quest
Step 1: Talk to Iwata
Your conversation with Iwata will trigger the quest, and during this time, he will tell you he is having trouble formulating a fertilizer. He needs this so the people of Watatsumi Island can plant more crops.
Iwata will request your assistance and ask that you meet him the next day to show you what he has made so far.
Step 2: Adjust In-Game Time
When the quest says to wait the next day, you can adjust the in-game time to 24 hours later. Once done, the quest will be updated, and you can now head to where Iwata is at.
Step 3: Find Iwata and Defeat Monsters
The following in-game day, you will find Iwata outside the crop garden and attacked by slimes. Defeat these monsters to progress through the quest.
You will find out the smell of Iwata’s fertilizer attracted those monsters. A while later, General Gorou arrives, saying he is investigating a stench disturbing the residents of Bourou Village.
Several moments later, a soldier will arrive to fetch Gorou because they have arrested a suspicious person claiming to be a researcher of the Academia and a fertilizer salesperson.
Step 4: Accompany Gorou to See the Suspicious Person
Upon arriving at the scene, the person that the soldiers arrested is Arlani—a Sumeru scholar who you met back in Ritou.
Step 5: Fetch Kaushik
Gorou needs more proof before he is convinced that Arlani is a researcher from the Academia, so he asks you to go and find Kaushik to help with the situation. He is also a scholar from the Sumeru and was permitted to research Watatsumi Island.
Kaushik is at a cliff southeast of Mouun Shrine. You can teleport to the Statue of the Seven and then glide down from there.
Step 6: Accompany Arlani to Help Iwata
Kaushik explained everything to Gorou and helped Arlani off the hook. Still, due to the trouble that Arlani’s actions have caused, she is asked to help Iwata with his fertilizer problems as compensation.
Arlani agreed, and you should take her to see Iwata so that the two can discuss the proper solution to the fertilizer problem.
This last step will complete the world quest. You can now go to Madarame Hyakubei, the Yashiro Commission Representative, to get the reputation reward and check your completion progress.