Come to think of it. How can you afford your everything? Temples plastered everywhere (cheap, but still), dai oni, researchers, forts, labs. In this dominion, with this few and this mediocre provinces, with unrest from all that freespawn?
What magic is this? Tell me your secret, you magnificent bastard you.
I'd venture Luck 3 and actual luck on top; possibly paired with gold sites and little upkeep on the army front.
Yomi is a nation that desperately craves diversity in its arsenal, though - it lacks an oppressive early game, but its national arsenal is easy to counter from the midgame afterwards.
Its fort army line is horrendous outside a stealth niche it does not excel at. It has a skeleton spammer but it easily puts a dent through Yomi's budget. Fire in general is not a great path when it comes to evocations, due to the double damage reduction tax.
The Dai Oni are what attracts players to Yomi, but it is is not a good supercaster, despite its price, and it only very dubiously qualifies as a SC chassis due to certain glaring weaknesses, being more of a heavy thug. It can do alright with a strong bless, but then it emphasizes its economic woes.
At least Niefel Jarls are actual SC material, and a good Niefel player can overlook the urge to rely too deeply on the niefels and push Niefelheim into a blood power with endgame aspirations.