He's all about "can't let people know he has unlimited mana", I agree that in this setting that's appropriate.... but... he then turns around and uses some questionable logic to get a very expensive 'training card' pass right there in the center and proceeds to spam his spells far beyond what he should have available?

Does he think they would never monitor those areas?

Then, he agrees to be a porter for some other group out of 'gratitude' to the other porter? WTF??? Just give the other porter money and they'd be happier! Instead he's wasting his time being a porter for someone else's group, but I'm sure the author will plot armor it to be a wipe so he gets everything.

Then, some big bad guy who's only rank B (I guess he's Cannon Fodder X?) tells him he HAS to go on a raid with them and that he doesn't have a choice...

Does the MC:

• Wisely avoid the raid where he knows for a fact they want to kill him (possibly by leaving the city/country or just staying in the mysterious hotel that that guy can't break in to?)
• Foolishly go to the raid even though he's still only rank D

The MC has no real ties AT ALL to where he's at.... family dead... no house.... only loose 'acquaintances' who are not even really mentioned. Naturally chooses to go to the raid.... since he has an IQ well below average.