* BaseBreakingCharacter: Usaida, after the anime started. While some people find him a rather funny character, others are very put-off by the way he keeps letting kids get out of his sight and them leaving the daycare by themselves so easily, as well as the fact he seems to be sleeping in his work all the time.
* EnsembleDarkhorse: Saikawa isn't actually featured that much in the storyline, since the Manga focuses more on Ryuu's activities at school, but he gets a ''lot'' of attention from the fans whenever he does show up.
* FanPreferredCouple: Between Inomata and Yuki's competition to be with Ryuuichi, a considerable amount of fans are cheering for the winner to be Kamitani.
* FridgeHorror: In Chapter 7/Episode 4B when Ryuuichi has a [[DreamSequence nightmare about the last time he sees his parents before they go on the plane they die on]]. Except that to make things more terrifying, the parents take Kotaro with them. Knowing they die Ryuuichi gets more worked up as Kotaro is his last living family member and all Ryuichi can do is watch and pound at an invisible wall stopping him from saving his toddler sibling. By the time the door closes and we are back to visuals of Ryuuichi in bed, we get a harder reestablishment that [[HatesBeingAlone Ryuuichi's greatest fear is losing his little brother and being left alone.]]
* HoYay:
** Even after realizing that the girl he fell for is Ryuuichi, Inui still gets easily flustered looking at him, especially when he sees him wearing an apron shirtless, a reaction that mirrors Yuki's (who is confirmed to have a crush on him).
** When Ryuuichi disguises himself as a girl, Kamitani quickly puts himself in the role of his boyfriend to get Inui away.
** Following that, when Inui is close to find out that the girl he likes is Ryuuichi, Kamitani threatens to send Inui flying if he hits Ryuuichi when he finds out.
** Yuki is actually jealous of Kamitani for being able to roll up Ryuuichi's sleeves.
** The first time we see Ryuuichi genuinely angry, it's not because of anything related to Kotarou. Rather, it's when he sees how [[spoiler: Hebihara-sensei, Kamitani's father]] treated Kamitani.
* LesYay: Quite a bit between Inomata and Yuki as they become closer friends. Yuki is quite prone to remarking Inomata cuteness and call her a pet name Maria-chan.
* MisaimedFandom: Yagi's hatedom largely comes from the fact that they believe him to be a pedophile and the story passing it off as a joke, however, the joke in the manga is the fact that he is always being mistaken by one or accused of being one, rather than actually being one. This is another reason why his scrappiness comes mostly from anime fans, as the manga has delved in his backstory and the reason why he's so fond of children ([[spoiler:Nezu and his baby brothers were the ones to keep him company when his parents couldn't be on his birthday when he was really young]]) and several characters have stated that he isn't one, just a weirdo, but deep down a NiceGuy.
* ToyShip: As about half of the series focuses on the interactions between the toddlers, this is probably inevitable. Most common ships are Kotaro/Kirin, Kotaro/Taka, or Taka/Kirin.
* Main/{{The Scrappy}}: A large number of people find Yagi's behaviour towards the children off-putting. This opinion is greatest within the anime-only community but there are a few who read the manga and still find the character genuinely creepy.
* ValuesDissonance: Hayato constantly hits his baby brother Taka when he acts up. This is meant to be PlayedForLaughs, but Western viewers may not find the act to be at all humorous, even when[[UnfortunateImplications (or especially when)]] it's depicted as harmless. This could be attributed to the more lenient attitudes toward family discipline in Japan, where striking one's child is generally frowned upon, but not considered grounds to call Child Services except in extreme cases.