You need 1000 draws in the five kage treasure to get Ay4 but you also have a 50% chance of getting susano saskay. If you got 20 seal scrolls a week it would take you a little under a year to get ay4. Ay4 appears a lot in the total spending rebate you c*so get him there for about 600$ USD or 550-ish EUROs. You could piece him out that would probably take longer than getting him in the five kage treasure though. I suggest getting ay3 from the Land of lighting treasure ay3 is very good.

for CF better Ay 3rd, for MB better Ay 4th.