Doing Susanoo's challenges (Not Aritama) count toward dungeon clears AND quest clears. I'm not sure how it EXACTLY works, but I think the lower end challenges like challenges I and II count as a "normal" clear, and count toward a clear for a dungeon. This means that doing challenges I and II count toward only 1 clear since they are considered "normal" difficulty. Challenges III and/or IV will count as another clear on "hard" and V is "Hell". I think. Either way it goes, I found this out by trying to do the Chief Daruma challenge to get some embroidered cushions without having to run to Kishin. After I cleared challenges II and IV, I got 2 lucky boxes from the Challenge Quest thing, and saw that it counted as both a dungeon clear and quest clear. The best part about doing these challenges is that most players are strong enough to take these bosses out in 1 hit. It takes less than 10 (in and out of the dungeon) seconds for a potential boss drop, 1k+ exp, and clears for lucky boxes. The exp part sounds trivial, but a boss like Benkei giving 3k+ exp for less than 10 seconds, and you can fight him 5 times isn't so bad.

Actually, u can get it from finishing Yakumo Temple too.

At lv.80+ you can finish it in 1 minute, along with all the money.

At lv.70+ you can finish it in 2 mins, along with all the exp/money.

At lv.60+ you can finish it in 3 mins (with fully upgraded weapons and high level skills).

And cushion now worth a lot