Woah this one was a doozy, Teppu is probably one of the more unique manga's out there with it's premise and it's approach to storytelling. Telling the story from what would normally be the antagonist of the story rather then the protagonist and honestly, Teppu wouldn't be half as good if it was written the other way around.
I'm going to be honest, when I first completed this series I thought it was extremely lackluster and not worth the 3 hours~ I spent binging it but looking back on it and thinking about the themes and the characters more and more I came around to it. More specifically, Natsuo the main character. I disliked her so much and hated that she didn't change by the end of the story but looking back, she did change or rather she WILL change. She's found something that she loves and that she can pour love into and when you pour love into something, that same thing pours love into you back. I shouldn't expect a person with 16 years of anguish to change in the span of 6 months, and once I came to that conclusion is when I truly saw Teppu for what it was.
In the end, the fact that Teppu is a good manga that I came around after finishing my read through.