Avan
Does the '10 year' duration hold some significance to the magus timespan? 100k spirit stones a day for 10 years, which implies that after 10 years, he's on his own unless he break through. There is also the part where if he had stayed with the dragon for 10 years, he would break through and become a magus without external help from the academy.
thanks for the chapter. Emery should accept, he will have a very hard time growing without help. He should just ask for a way to travel between Earth and their planet, saying he needs to go to Earth first. If he needs an excuse (since he might not want to tell about a secret Dragon master), he can explained it with the requirement to increase his bloodline power.
Late to the party, but he should renegotiate. The deal is very good, but 100 years of servitude is not something he can agree to, as he does have connections on earth. Options are, delaying the service, removing many benefits to get the service as a x jobs version (with choice to do it), or refuse outright and cash out some benefits (like 200,000 stones) instead of the favourable deal.