1. First of all, the rare minerals mined in the mine and the cultural relics excavated from the underground were donated to the only library in the town, as shown below:

2. In order to trigger the story of the library, the total donation must reach 60, as shown in the following figure:

3. When the total donation reaches 60, when you get up and open the door the next day, you will find that the librarian has come to visit in person, as shown in the following figure:

4. Talk to him and get a rusty key, which can be used to open the iron gate of the sewer, as shown below:

5. Open the backpack and click the skill option to view the rusty key, as shown in the figure below:

6. The location of the sewer is just the location of picking up green onions in spring, as shown in the figure below:

7. Go to the sewer and right-click the iron gate, as shown in the figure below:

8. Prompt to use the key to open the door successfully, so that we can enter the sewer, as shown in the figure below: