The stray yukkuri in DoD has similarly little encounter rate and 1/1000 recruit rate in GoS. The hookshot areas have decent chances to encounter a yukkuri and some have a healing circle so it's only one screen transition away from enemies. I never was able to recruit the base yukkuri, so would you like my save to test? They would be trivial to kill with my lv90+ party. ...holy crap, I was going there so my save would already be at the right spot, and I ran into a Stray Yukkuri; I didn't know they could even appear there, I'd done a good chunk of grinding for Star Platinum in this area. Anyway, the goal would be a normal yukkuri, but that's a bonus :V ...and there's another normal one, and another stray, goddamn.
Okay nevermind, it just doesn't seem to want to save there. That kind of ruins the ability to test. :T Better plan, test with the King Yukkuri spawn in the final basegame area. Go down one screen and try either of the two enemies to the left. To ensure the kill;
1.Yuyuko casts Quicktime with Sakuya. If this isn't going first, have Sanae cast Rapid Stream. She has this move on two shikigami in case you want it turn 2 as well.
2.Sunny casts Banzai Attack with Rinnosuke. This is a chasing skill, so if you need rapid stream+quicktime turn 1, use it turn 2 instead for more activations. This skill should make it extra easy to get the kill.
3.Everyone has their three most relevant physical attacks equipped. Don't worry about investigating their shikigami skills imo. Kogasa's attack power is twice as high as the rest of the cast here, by the way.
4.If a turn 2 King Splash is actually worrisome and killing people, you can have Yuyuko cast Dark Illusion with Koakuma turn 1.
...okay nevermind. Somehow tell me how to make your save file ACTUALLY SAVE ON THE SCREEN. I know for a fact you can save on the healing circle/final boss screen at the end of the maingame final dungeon. I know this, I have a friend's save I can load that's on that screen. I've never been able to make my saves actually load on healing circle screens even though my friends do it. FFS.
...anyway.
The hookshot takes some hours to get. Getting Satori takes another couple hours, as you have to beat one of the Tower bosses for her event to appear. (She's recruited as you leave the tower.)
The recruit rate for monsters is fixed per -type- of monster, to be specific; there's 1/1 chance, 1/2, 1/4, 1/8, 1/16, 1/64 (ugh), and 1/256 for yukkuris. 1/1000 is only for stray yukkuri, because jerk developers. There is no increase in chance to recruit enemies as you defeat more of them, just new rng rolls. So, yukkuris are nearly impossible to recruit without just getting incredibly lucky.