The MC does seem to be able to level up fast, but has a issue that there are no drop items from the monsters he kills, which the country does not like since he is being trained by the military and the nobles take all the military's drops for themselves (the nation seems to have extreme nepotism and corruption issues, with the nobles abusing the leveling and party shared experience mechanics to keep themselves stronger then the commoners). Oh and the drops include (the only legal source of) money which is explained to be a gift from the Gods, as nations do not mint their own and it is illegal for someone to make their own coins.

After a month of training the MC has reached a decent level and is sent on a (sand based) ship to a neighboring nation, only 2 people see him off, except it gets attacked by monsters along the way and everyone other then the MC and the crew who took off immediately and never returned.

The MC takes what he can from the wreck and sets off, eventually reaching a loan oasis (it is surrounded by monster nests and there is no safe way in or out) where he meets the 2 female companions. Both are former aristocrats of the summoning kingdom, including the King's sister, but were effectively kicked out (despite being very skilled combatants and the desert monsters being very real threats) for not lining up with that worlds standards of beauty. This is one thing I find amusing considering how often it is ignored, but the standards of beauty have varied widely over the centuries, and their worlds standard for women seems to be an strictly defined exaggeration of a low resource starvation prone setting (a lot of beauty standards come form what your appearance says about your social and economic status, and in a world where resources are scarce and starvation is prone being overweight becomes the standard because it means you are not starving, where s when fattening foods become cheaper and plentiful like in the developed world becoming thin becomes the standard since it means you are eating better foods). Yes, the image obsessed king demoted his sister out of the royal family and and sent her to an effective prison simply for being to thin...

They start passing the time with the only entertainment available to them of leveling, and when the MC crosses level 200 (For reference the MC was early 70's when he finishes him month of training and IIRC early 120's after the swarm destroyed the ship he was on, but the princess is in the mid 500's when they meet) he gains his net shopping skill (develops in ch 16, tests in ch 17). Which allows him to purchase goods at the equivalent price of modern Japan (but with a 100% of price delivery charge)

Afterwards they go to lead an easier life with the benefits they can gain from the skill (there are very few food sources at the oasis, so the ingredients are a major benefit), until the oasis starts to dry out and they need to leave to find somewhere else they can live.