I love that the teacher and kids are so welcoming and kind to him. But at some people I hope he confronts more negative emotions and gets to learn how to properly deal with them.
I'd be fine with that because Mamoru is a natural progression of the plot. It's not like the author deciding randomly to focus on an entirely different set of characters that have almost nothing to do with the main cast or premise. This is the child of the MC and wife (with no emotion) and going into their development and how it continues to grow both the main and title character through them raising a child. Just like parenting does in real life. It's not derailing the story here anymore than it is in real life.
I love how the entire office is slowly joining the watch party. Truly the expected result from a country where there's a TV show of children doing their first errand.
"What the fuck are you doing? Get back to work!"
"It's my boi's first day"
"And you're sitting here writing up documents?! I guess I have to help you watch the boi, then"