I can understand him expecting obligatory chocolate from any of the moms just because that's like a thing to do for teachers generally (also they're all friends)

But Yukari in particular!!

Just...I have feelings.

And a shit ton of context for people cause I can't stop talking now:

Gakuen Babysitters is a wholesome manga in LaLa magazine (along with Natsume Yuujinchou) by Tokeino Hari (who also made Onii-chan to Issho).

The series focuses on the Kashima brothers- Ryuuichi, a ninth-grade student (last year of junior high) and his younger brother (preschool age cause he can't write yet) Kotarou- who are orphaned when their parents die in a plane crash. They are taken in by the chairwoman (technically everyone calls her chairman but whatevs) of Morinomiya Academy, who lost her son and his wife in that same class.

At Morinomiya, there's a daycare where teachers can drop off their kids, and in exchange for the chairwoman taking care of him, Ryuuichi has to help look after the teachers' kids.

While most are in preschool still, there's one baby, named Sawatari Midori.

Her mother works in the office and her father is an archeologist.

The only other girl in the daycare is the drama teacher's daughter, Kumatsuka Kirin. Kirin's father is a photographer, and he is very overprotective of her.

So, Inui.

Inui is a guy who starts off with a massive crush on Midori's mom, and after a huge misunderstanding- she says her husband is somewhere far away and Inui thinks the guy's DEAD instead of on an archeological dig- Inui meets Ryuuichi while trying to help care for Midori. Afterwards, he admits that even though Ryuuichi's his kouhai and has even less romantic experience than him, he's actually kinda cool.

After that experience, an embarrassed Inui also helps Kotarou with various little tasks (and gains the nickname "Mr. Mask/Mr. Maks") throughout the series. But that's neither here nor there.

So, that's how they meet.

Later on, for the cultural festival, the Morinomiya Academy daycare plans an event for parents, and Kirin's father (remember him?) is able to make it! But because he's overprotective and perhaps even a misandrist, Kirin's mother has Ryuuichi, Usaida (the only actual adult male and main caretaker), and Kamitani (the biology teacher's older son and Ryuuichi's classmate who also helps at the daycare) dress up and pretend to be girls so as not to incur his wrath.

This ultimately fails, though notably he is still warmer towards Ryuuichi than towards the other two.

Before that though, while he's still dressed up, Inui catches sight of him and thinks he's a girl.

After a series of comedic events, he ends up asking "Inomata" (the name of a girl who helps out sometimes, and the name Ryuuichi accidentally gives his female persona) on a date. Ryuichi agrees and, after a while, finally reveals himself to be, well, not a girl named Inomata (except he still gives off mom-vibes).

They part ways, with Inui continuing to help his crush's little brother, but still also stumbling upon crossdressing Ryuuichi as Ryuuichi still helps out the theater teacher.

With no context, Inui thinks maybe Ryuuichi is actually a trans woman (who's either in denial or closeted) after his younger sister tells him that trans women exist.

More shenanigans ensue, and Inui ends up inviting Ryuuichi and Kotarou (not "Inomata" and her sister "Kotoko") to the aquarium with him.

And that's as far as the manga got with the two of them on Mangazone. The anime ends before Ryuuichi even tells Inui the truth.

....Watch your enthusiasm, Inui...

Anime: Gakuen Babysitters Audio: Curb Your Enthusiasm theme

Mask man, the hero Koutaro admires!

The actual man beneath the mask: