Maybe I'm really stupid but I have no idea how to continue the task that says: "Hazuki might've been attacked by monstrums. The miasma detector can find traces of monstrums. I'll thoroughly search the residential area." I went to the residential area and interacted with the miasma there, but I'm not sure what to do now or where clues are.. :c
I am trying to remember what the next step for that was, but, for the life of me, I cannot remember. All I can offer is to check the usual suspects.
Check around the town and see if there are any other Miasma spots.
Talk to Memoria, talk to Hazuki's Mom, talk to Hazuki at home and at school, talk to Mado and the other kids in the photo club. If all else fails, go to sleep and check on everyone again. See if there are any new missions.
The only other things I can think of is to try talking to your father and check out the first 'dungeon' in the sewers. I seem to recall there was some point where you had to go back into the sewers to advance the story, but I can't remember exactly when.