I was surprised at how emotional it made me when it's only 16 min long (got a little choked up)! The focus is really on the relationship between the son and mother and the story is relatable from both character's perspective. The story overall is sweet.

On the Blued YouTube channel (in the USA).
The review by Giuca is also good and summarizes the details well.

GENERAL SPOILER
My rating is reduced due to the scene that starts with the schoolmate forcing himself on the lead boy, which is brief and not at all graphic but trivialized with a light-hearted attitude. The lead boy has invited an anonymous boy from online to try things out with but changes his mind when he sees it's the school bully. The bully turns out to be very sweet to the boy but the way they start is problematic and didn't need to be written that way.