After an anime adaptation has kept up with the manga, filler episodes are often required to bridge the gap in time. These arcs and episodes are primarily anime-exclusive, and as such, they usually don't significantly advance the plot. Because filler episodes are more likely to have out-of-character situations, many fans frequently label them as "skippable" and others even outright detest them.
It's a rare instance, but Katekyo Hitman Reborn! stands out because its filler arc enhanced the overall plot of the series, earning it the universal approval of fans.
How did Katekyo Hitman Reborn come to be?
Katekyo Hitman Reborn! is a shonen action comedy about an exceptionally untalented teenager named Tsunayoshi Sawada that's bad at studying and sports, physically weak, and often the target of bullying at school. It's gotten so bad that almost everyone, even his own mother, has taken to calling him "No Good Tsuna." One day, Tsuna's mother finds a flyer advertising the services of a home tutor named Reborn. Hoping that Reborn will help whip her son into shape, she quickly gives him a call, thus kick starting the events of the story.
But Reborn is more than just a tutor. He's the world's number one hitman -- who also happens to be trapped in the body of a baby. To add to this, he tells Tsuna that the biggest mafia family in the world expects him to be their next leader which, predictably, leads to all sorts of ridiculous shenanigans. As Tsuna learns to get stronger and gain more confidence, he also finds himself befriending a slew of unique and interesting personalities that Reborn hopes can be recruited into Tsuna's famiglia -- to Tsuna's never ending dismay.
What's the Storyline of Katekyo Hitman Reborn's Filler Episodes?
Katekyo Hitman Reborn! has two filler arcs: "The Arcobaleno Trials" and the "Inheritance Succession" arcs. "The Arcobaleno Trials" goes into more detail about the mysterious curse plaguing the Arcobaleno and provides a bit of backstory to each one. It also adds a bit more depth to the characters involved, as Tsuna and his Guardians are paired with them, providing interesting matchups and dynamics that weren't present in the original manga. It also provides some much-needed character development for certain characters that didn't get as much screen time in the manga.
The "Inheritance Succession" arc provides new background information on how the Vongola family was formed and explains how the founding member, Primo, made his way to Japan. It also gives more screen time, lore, and information on the founding members of the Vongola family who, at that point in the manga, were characters that were mostly shrouded in mystery beyond bearing a striking resemblance to Tsuna and his friends. Overall, both arcs add some much-needed depths to the world of Katekyo Hitman Reborn! in a way that most filler arcs fail to do.
How Are Katekyo Hitman Reborn's Filler Episodes Better Than the Anime?
Katekyo Hitman Reborn!'s filler arcs are unique in that they clearly weren't written as fluffy breather episodes. Instead, they expand more on the source material by including more important details and information that weren't present in the original manga. Rather than feeling like episodes that are just there to buy time, they feel more like an expansion to the story's narrative to the point that they don't feel like filler episodes at all.
As with a lot of anime adaptations released in the early to mid-2000s, Katekyo Hitman Reborn! has made a good deal of changes to the anime adaptation. While some of these changes didn't work, most of them were received positively by the fandom -- including the anime adaptation's unique take on filler episodes.