After replaying more than I care to admit I've found all those hamsters. Perhaps would've been an obvious one but I think it would've been rather funny to have one hidden when MC enters Hirano's office and notes on one of the smells reminding him of a wild animal.

You've got me really curious about what MC is though. Not cause of that old guy, though he reinforces it. Might be reading too much into some of these things but so far it seems MC has:

• Fast regen
• Seems resistant to other myths abilities (Miko paralyzing him, Yukari in his dreams)
• Some odor about him (presumably when adrenalin kicks in?)
• Heightened senses (Was that sense of urgency to wake up when Miko tried to paralyze him. Also at least smell since he noted something that made him think of a wild animal when Claws was in Hirano's office. Seemed to actually feel when his stalker was, well, stalking)
• High strength since he could still get up despite the Obariyon sitting on him
• That religion Jun's family was a part of having some way to track specifically him (or whatever he is/is meant to be)