Bronze
1. Play with the boy at the park.
2. Help the man who is wallowing in sadness [you have to find him next to the trash box thingy in the back alley [路地裏通り] three times, then once more outside].
3. Find the horse in the back alley [路地裏通り].
4. Play with the boy in the back alley [路地裏通り]. I don't really know what triggered it but there will be a monster different to the shadows around the western area. Defeat it to reveal a small hole. Progress there.
5. Help the suffering coughmasturba-cough man in the male bath place. I believe this can only be triggered after talking to an npc who mentions something about their spouse or son or someone going to the bath and hasn't come back in a while.
6. 'Help' a man out in the toilets using a convenient hole. From what I remember, you have to have defeated the monster for Bronze 4 and interacted with the chest in that area for this to work... or maybe was it overhearing an npc talking about the hole? I forget.
7. There will be an npc who talks about how children [or was it boys?] that used to play around the park area has disappeared. Search the back alley, around the south east area, where there are a group of them and talk to them.
8. An npc who is running in circles at a really fast pace appears. Talk to them, then go to... uh... middle bottom? of the back alley. There should be a girl and two shadow monsters surrounding her. Fight them.
Silver
1. Unsure if this is 'defeat all types of monsters once each' or 'defeat all monsters' but anyway related to hunting monsters. Off the top of my head there is the monster for bronze4, the goblin near the rats on the northern area, the statue thingy to the north-east, the bees to the mid-east, man-eater plant in the mid-east, cerberus to the south-east, slimes, ghosts, snakes, crows and bats. Not sure if that underground boss thingy counts as well.
2. Find the 'cameo' character number 1.
3. Find the 'cameo' character number 2. I believe the 'cameo' characters were mentioned in the previous posts somewhere.
4. Give the medicine to the sick sister and clear the game.
Gold
1. Gain all bronze/silver medals.