Oya No Kao Ga Mite Mitai
A lawyer is dumped by his unfaithful wife in a gay cruising district and has a one-night stand with a guy who turns out to be his son's kindergarten teacher. Taiga, the man's son, is one of the most charming child characters I've encountered in manga. He openly declares his love for sensei, going so far as to loan him to his father until he's ten years older.
Sensei wa Butchozura Shite Yatte Kuru
Sister story to "Ookami Papa wa Hitsuji Tsura shite Yatte kuru." A man still getting over the emotional fallout of his last relationship has been single for five years and pining for his best friend. One afternoon, when he's picking up his nephew from daycare, the robotic teacher at his daycare calls him out on his lovesick expression - and then begins to insert himself into his life.
Otona Gokko!
A flirty kindergarten teacher harbors not-at-all-secret feelings for his coworker, who gets entangled in his family's absurdities (eg. stalker father, creepy twin brother) and somehow, we're supposed to care about their "connection." I like this author, and I love the scanlation team that picked this up (Exiled Rebels), and maybe it's because MDZS has ruined me for all love stories for the rest of my life, but this did nothing for me.
Kuro X Koi