Dungeon 9 was definitely too easy. Having had a number of special attacks unlock late into Dungeon 8, but be useless due to that dungeon's meta, I tried them out here, and following up Mami's Ribbon Tie with Firewind and Lovely Barrage (and later Gun Volley and Heartfelt Barrage) made short work of most opposition. I managed to defeat the boss at party level 35 (Kyouko had just made 36), having only lost one girl at any point, and after encountering exactly zero fetish events... not counting failed bikini thefts or the boss's tentacle grab attack. Nothing even managed to land a parasite on a girl until well after defeating the boss, so the rate on that probably needs a boost; it would've been a lot harder dungeon if I was getting stat and XP debuffs prior to defeating the boss and hitting the level cap, instead of the other way around. Of course, as a beach episode... it's kind of on-theme for it to be easy? This tickles a vague thought I've had for a while; one of the major factors in how hard a dungeon is seems to be how easy it is to avoid the fights. Forced encounters with large groups of enemies to pass chokepoints makes for difficult dungeons, but more open terrain and enemy patterns that make it easier to sneak past makes dungeons quite a bit easier. That's not the only factor that matters, but it's a big one.
It'd be a QoL improvement if the mermaids were visually removed from the fight after running away, like the bombs and the tentacles are after doing their attacks. Speaking of the bombs, they didn't really seem to add much to the dungeon? They weren't dangerous enough to need to defuse (although having Mami start the encounter with String Up on a bomb mostly negated its threat), and they didn't add any fetish aspect to the dungeon. In grinding out the titles, I eventually became unhappy to see the mermaids, since they became straight up physical attackers with nothing to steal (it didn't help that they often disguised themselves as tentacles on the map)... but the bombs were never fun to encounter, especially since they often came in roadblock singletons. Considering the previous dungeon's more interesting mechanics... maybe the bombs could blow up on *one* girl, covering her with pheromones and giving her a lingering debuff that makes the other enemies more likely to target her with their more dangerous techniques?
As a final note; I decided to give the boss a second try with a fully stripped and parasitized party, just before leaving the dungeon, and it put up a real beast of a fight! Even going in with the usual full debuff stack against its attacks, the stuns from the parasites and the boss's own tentacles made it very close. If the many tentacles I fought in the process of exploring the island, flipping the switches, and opening all the chests had used their parasitic attacks more frequently than never pre-boss, I'd have had a much harder time of things.
Dungeon 10 is probably my new favourite, thematically speaking. The relentless focus of all the enemies in lowering Resistance made them comparatively gentle, and there was plenty of extra medicine drops to ensure that I could easily recover from any lost HP. Instead, it was just quickly making my way through enemies to switches and chests, while on a slippery downward slope that made their techniques more and more effective. Special Attack aoe spam remained the obvious way to go here, given the many, many forced four-enemy fights; it worked out just as well as it did in the previous Dungeon, but this one was just a lot longer. The repetitive nature of the rooms was thematically on-point, giving me real "have I been here already this time?" thoughts when checking everything. For some reason, Mami consistently picked up a lot of Suggestibility despite not being the taunt-tank; I wound up using nearly every Brain Rewirer on her to fend off the debuffs. The re-use of the grovel animation felt a little off, here; seeing the girls suddenly without all that hypno gear when they knelt was incongruous. I didn't actually lose anyone before confronting the boss, and felt that my party was still in good shape when I did face it, level-capped and ready to go. The group straightjacketing was unexpected, but I'd weakened it enough while I still had moves available to pull off a win anyway.
Interestingly, the straightjackets stayed on after the boss fight, though I couldn't find an item or trait to explain why. Though hot, this rather interfered with my ability to do anything else in the dungeon after the boss fight. Fortunately, I had plenty of Brain Melters on hand to get the title stats, and the enemies' Strip commands still had mechanical effect while straightjacketed, even if they didn't have visual effect, so I was able to get all the titles without having to reload a save. Still, if anywhere at all in the entire game needed a post-boss item to remove a fetish effect, it's this one, given the way the jackets prevent most of the other enemy commands from working correctly; it'd have been nice to have had a chance to play around with the enemies and their hypnotic commands while grinding the titles instead of just getting the right numbers down and leaving. Unusually, this boss didn't unlock an easy path to the exit after being defeated, so I needed to defeat it again in order to leave, with the whole party bound in straightjackets and unable to fight properly. Madoka's Inner Strength came in handy, allowing a narrow win anyway... but it was a very strange fight.
As a sidenote, in this dungeon, Mami learned Breaking Shot, which I'd hoped would be a good status effect. It was not. Using it on a single enemy and seeing the word stun flash by them twice in quick succession before they attacked felt particularly unfun; like they hadn't been stunned at all and the game had lied to me. Yes, I get that it'd be too effective against bosses and such (I tried it on the boss out of curiosity, and it did the same thing); but it's very genre-standard for bosses to be immune to the cheesy spells, and it'd help in making singleton fights less annoying. Since there weren't any normal enemies dangerous enough to be worth locking down, it felt like a worthless addition.