Monster: The taste of sugar
I love all of the tertiary characters in Monster. Urasawa's filler chapters are some of the most enjoyable parts of his books. Usually, it's because he peoples them with great one-shot characters. The eighteen year old girl providing medical treatment to her fellow Vietnamese illegal immigrants...the mercenary and the little girl...the country doctor with a troublesome patient...the British couple on a very sombre vacation...the ex-Nazi soldier, begging the place he loves for forgiveness...the psychologist performing a new experiment on children in an orphanage...they come and shine their own individual lights into the darkness, then fade away as the plot resumes.
I'd hate to inundate you with posts, so, I'll only share my favourite: Mr. Rosso.
Context: One of our protagonists, Nina Fortner (I don't want to say too much about her importance to the plot, so suffice it to say that she wants to kill Johan for her own reasons) has taken a job in a small Italian restaurant, owned by Mr. Rosso. Rosso is a kindly old man, who happens to cry at old movies and loves good food. Nina had an ulterior motive for taking the job with him: it turns out that Nina is aware that Rosso has a dark past as a professional hitman. Rosso is now telling her a story from those days.
Reads right to left:
I think the other thing that makes Urasawa's filler so good is that even when it doesn't serve the plot all that much, it does serve the themes. Rosso doesn't find redemption, in the most literal sense. Instead, he simply reclaims his humanity, and all of the good things that come with it ("the taste of sugar"), by ceasing to commit crimes against others. As the loss of humanity plays an important role throughout the series, Mr. Rosso's example becomes ever more important, long after his effects on the plot proper have ceased to be felt.