"There's only so far he can go relying only on his own strength and the griffon he's tamed."
Wait, what? A griffon is a rank A creature, which means it, by itself, is comparable to a rank A party of adventurers, right? I don't understand how you would be able to underestimate him like that.
It'd be nice for a protag to actually romance some guild receptionists for once. Every time I read an isekai, guild receptionists are hot, but the protags never touch them.