Miia leaving herself completely vulnerable to Kimihito. Up until that point, her stripping down and acting like The Tease was played for laughs or fanservice, but this? This really hammered home that her feelings for him are genuine: she loves and trusts him with her very life. Kimihito is so amazed by this he has no idea how to react.
The first time Kimihito and Centorea hold hands. Her expression is a combination of this and Crowning Moment of Funny, simply because of how happy she looks.
The bonus chapter depicts the first signing event the author has ever done. Highlights include a huge line of fans waiting outside despite the cold, heavy rain and fans coming all the way from Taiwan and Canada.
When Kimihito decides to keep Suu and Miia and Centorea have a freakout, he tells them to think of her as a kid. Cue two sweet fantasy thought bubbles about them each having a family with Kimihito.
Which quickly segues into a Crowning Moment of Funny when Centorea once again finds herself conflicted over her emotions for her "master."
Papi is normally childlike and irresponsible, but surprisingly she shows herself to have a strong motherly streak and to be very good with children. This leads to Papi being the one who more or less "adopts" the even more childlike Suu — giving her a name, playing with her and protecting her — even when the other members of the household are still reluctant, angry, or skeptical.
The reveal of how Kimihito caught his cold: running out in the rain to escort a trapped Suu home.
Suu nursing Kimihito. By giving him water from her own body, no less, since it's well established that water is literally life to a slime.
Suu speaks for the first time:
Suu: Well, it was Suu's fault that you caught a cold...I should apologize as well. (Beat) But Suu doesn't mind! Because she loves her master!
Kimihito and Miia almost...almost kiss for the first time. Mero kills the moment, but it's the thought that counts.
Kimihito's heart pendant gift for Miia at the end.
The flashback where Ms. Smith is bending down to comfort young monster girls after rescuing them from traffickers. For someone who usually acts lazy and irresponsible, it's nice to see she really does have a heart.
When Ms. Smith and her people show up and it appears that Kii's going to be punished, Kimihito starts arguing with Ms. Smith about it. Keep in mind he knows absolutely nothing about the girl he's defending, and he's doing so anyway because she's friends with Papi.
Kimihito assures Centorea she is most definitely not worthless.
Other than Zombina's (which was CMOF), Kimihito's dates with MON are filled with this when they realize he's as nice and nonjudgmental as he appears. Manako's is particularly WAFF-y.
Even Zombina's was very heartwarming, when she wasn't teasing him that is. One moment in particular was when he was sewing her hand back on after the stitching came loose and she compliments him on how he's so unfazed by her weirdness, saying that guys nowadays can't really handle gore all that well. Kimihito replies with:
Kimihito: If I saw a real dead body, I'd probably be grossed out, but... You're you, so... You're not a dead body, Zombina. So, it's okay.
Miia really shows how much she loves Kimihito. First she saved Kimihito from being drowned by a love-crazed Mero. Then she tries to help him spit out the water, although in true Miia fashion she accidentally hurts him in the process. Miia then realizes that all of their attempts to help Kimihito escape the dullahan only end up hurting him, so she resolves to stand her ground and fight off anyone who tries to harm him. When she gets wrapped up by Rachnera, who says the dullahan is trying to give Kimihito a Mercy Kill, Miia demands that she die too so she can at least be Together in Death with him, even though she's clearly terrified of dying. Finally, when Kimihito tells her that he'll marry her if he survives, her first response isn't to celebrate, but concern that he's triggering a Death Flag.
Rachnera also shows how strong her love for Kimihito is. When the dullahan points out that Kimihito constantly suffers injuries by them, she decides that she'd rather let the dullahan give Kimihito a quick, painless death than force him to endure so much pain, in essence putting Kimihito's happiness before her own.
Centorea's fantasy of becoming disgraced knight adventurers with Kimihito. While still a fantasy and quickly ruined by her master falling off the saddle and smashing his head against the pavement, it's a really sweet dream.
Another point for Centorea. When the Dullahan appears behind her, Centorea doesn't hesitate in staying to fight her while Mero gets Kimihito away from the Dullahan. Keep in mind that, at this point, all of the girls are convinced that the Dullahan truly is the Grim Reaper and a deadly dangerous threat. It's obvious that she's willing to fight and possibly even die to keep him safe.
The market street vendors offering Kimihito and the girls all sorts of freebies and kind words. Before that, their efforts to hide all the poultry (Papi) and fish (Mero) from the girls to avoid offending them. It really speaks to the efforts of the program that regular folk would go to such lengths to respect a different culture—or rather, species.
When Suu hears Kimihito talking about how everyone eats so much, she tells him he doesn't need to get any food for her, as she can eat anything. Kimihito thanks her for the thought, but says everyone should eat the same food at the same table - they're family, after all.
Despite it being clear that most of the girls don't particularly like Rachnera, they were willing to put Ren through "tests" just to make sure the family that sold her before has actually changed. Not to mention when Rachnera doesn't put up a fight, the girls look to Kimihito to stop it.
This one can be easily overlooked, but when Kimihito returns home he gives each girl their own brand of coffee (and a large water for Suu), showing he recalls their own tastes.
Kimihito flat out states "No way" to Ren when she asks for Rachnera back, clearly seeing that she doesn't see Rachnera as a person but as a challenge like one in a video game.
Rachnera, wasted on coffee, confesses her thanks to Kimihito for defending her, then outright stating that she loves him for why he did it.
After the main craziness is over, during the Bathtub Bonding. Miia's mother tells her that the reason her aphrodisiac didn't work on Kimihito was because the poison was designed to turn the victims hatred for lamias into lust, and Kimihito never hated lamias in the first place.
After chasing Kimhiito and her daughter all day, Papi's mom reveals that she was only there to see her daughter, and only attacked Kimihito because he had an embarassing picture. Oh, and there's the fact that she broke the rules of her race that frowned on monogamy because she loves her husband. Which turns into a funny moment when she reveals that nobody follows that rule anyway.
Centaurea's mother's past. It's clear beyond a shadow of a doubt how much she and her 'Teaser' love each other, to the point where the 'Teaser', a scrawny little human, would put himself between her and a rampaging centaur stallion in order to protect her.
When Rachnera states that due to how her body is she can only hurt people around her, Kimihito cuts her off and tells her he understands that she truly cares for everyone and does everything she can to not accidentally hurt the people around her. This comment causes her face to turn crimson and her usually sharp tongue to fail.
Out of all the girls, Rachnera is the only one to really pull her punches around Kimihito. Out of someone so hard-edged and snarky, this is understated but significant sweetness.
In a way, Lala's confession to Kimihito. She states she has no interest in chasing him like the other girls do because she knows that one day he will die. And since she is part of the underworld they can be together then. Essentially in her own way she stated I Will Wait for You:
Lala: I'm a dullahan...so yer soul will be mine once ye die. That means ye need never fear the reaper.
Yukio has a good host family and is in love with the young master of the family.
And in the end, thanks to Centorea's idea, other guys and gals may find love too. The last panel is a rather cute scene of four guys hitting it off quite well with a Lamia, Kobold, Lizardman and Elder Devil.
Small detail, but Rachnera stops lurking in the shadows for this chapter, and sticks with Kimihito in the onsen's main pool. The key part here is that she overheats in conditions that hot, but tries her best to grin and bear it so she can be close to Kimihito.
Cathyl's relationship with the guy that owns the farm. Yeah, she tried to murder the guy because of her bad habit of not remembering names, but when she realizes that she was in the wrong, they make up pretty easily. Heck, the guy probably goes through quite a bit like Kimihito (not as much as him but plenty considering).
Papi and Suu are heartbroken at the thought of Mero leaving forever. Considering the girls are all rivals with each other, it's sweet to see them become such close friends.
Rachnera making a genuine effort to cheer up Papi and Suu. Compared to earlier in the series where Rachnera got a kick out of teasing and messing with the others, and her frustration with Suu, it shows how much she's softened up over time.
Rachnera putting in effort to help with dinner solely because Kimihito asked for her help.
Lala spills her heart out to Kimihito about how she wishes to save terminally ill girl Yuuhi's life. Kimihito gives her the push she needs as she elects to give Yuuhi's life back instead of just letting her die... Okay, well, she did it by turning Yuuhi into a zombie, but the sentiment is still there.
It's a tiny background detail, but the next morning Yuuhi can be briefly seen with one of the cuddly toys Lala got her, implying she appreciated the gesture.
The omake after that chapter where Yuuhi is hanging out with Zombina, being mentored in what she needs to know to live as a zombie, is really sweet. Zombina looks like she's quite happy to become a Cool Big Sis to Yuuhi. Oh, and Tionishia brings in a huge stack of sweets as gifts for Yuuhi, even if the size of the stack does promptly cause her to trip over and break Zombina to pieces.
When Kimihito and Lala visit MON to apologize for turning Yuuhi into a zombie it turns out that they're all fine with what happened, including Ms Smith. According to Tionishia Yuuhi's parents even thanked them for it. Given how worried they all were the previous chapter, it's nice to hear that it didn't end badly.
Zombina very angrily rebukes Kimihito when she discovers he got a pretty nasty cut on his shoulder trying to protect her from Shiishii, insisting that risking his life to protect a corpse is reckless and stupid. Kimihito reminds her that she's not just a corpse, she's a person and his friend.
After helping Doppel take out the orc rapist, she decides to reward Kimihito by transforming into any woman he desires. Kimihito refuses the reward, saying he would rather Doppel be herself...but asks her to Please Put Some Clothes On (which, as a later scene shows, she does. She's rather embarrassed about it, though, especially when her teammates wonder how Kimihito managed to convince her to wear something other than her own hair for the first time they've known her.)
Kimihito, Tionishia and Polt go out of their way in order to help Kii, who's feeling a bit under the weather.
Tio in particular ends up being too warm. To the point of freaking out Kimihito.
Kimihito: Ti...Tio is dangerous... Once she has you in her warm embrace, there is no escape...
Kimihito and the rest of MON go out of their way to help Manako get over her social anxieties.
Seeing the formerly sickly Yuuhi cheerfully playing along with the neighborhood kids warms the heart.
Kimihito´s speech to Kino, a really, really, REALLY shy Matango girl, which not only comforts the poor girl, but touches her heart to such a degree that she has to pull her cap down to hide her blushing cheeks out of sight.
Also, the rest of the household´s warm welcome and reassurance to the poor girl after the whole spore incident as well...
Papi almost drives vampire girl Kyurii crazy with her constant goofing off and running around the extraspecies expo. Just when Kyurii is about to get fed up with her, Papi reveals that her wandering had a purpose: she was actually looking for the thing Kyurii lost earlier without noticing (a locket with a picture of her with her father), just because she wanted to be nice to a friend. The two actually just met, but Papi says that with the warmest, sincerest smile on her face, so Kyurii can't help but smile back to thank her.
When Kyurii tells Papi not to call her a friend anymore in order to protect her, Papi talks about how she struggles through life with her poor memory and scatterbrained mind, before saying she'll never forget something that's really important. This is followed by Papi hugging Kyurii, finally getting Kyurii's name right, and saying she'll always call Kyurii her friend. This causes Kyurii to start tearing up.