After Clock Tower.

1. Harbor: Take the (left) boat to the southern island.
2. Pier: Talk to the guide. This opens the path to the Village.
3. Village: Talk to Mint, the Elder and the guy at the Inn.
4. Sleep (in the left bed).
5. Talk to the guide. (Guy close to the village entrance.) This opens the path to the volcano top.
6. Volcano top: Talk to the guide and make your way through the crater to the conveyor belt area.
7. Conveyor: To the the toilet, promise to say nothing. This allows you to enter the office area.
8. Office: Listen to the conversation at the “boss door”.
9. Conveyor: Back to the toilet and meet with Kotetsu. He opens the way through trash chute into another part of the volcano.
10. …