The debate between canon and filler is one of the longest-running conversations in anime fandom, and My Hero Academia provides a prime case study. With over 400 manga chapters and a sprawling anime adaptation, some arcs feel like seamless translations while others are padded with extra moments designed to let the source material breathe. Few arcs crystallize this balance better than the Joint Training Arc. Adapted in the fifth season, this storyline—a head‑to‑head battle between U.A.’s Class 1‑A and Class 1‑B—is a cornerstone of character progression, yet its anime presentation blurred lines for viewers expecting a one-to-one adaptation. This article analyzes the Joint Training Arc’s canon and filler elements, examining how each layer contributes to the series’ larger narrative, elevates character arcs, and sets the stage for the catastrophic events that follow.

Understanding Canon and Filler in My Hero Academia

In the manga industry, canon denotes material that originates directly from the original creator’s pen. For My Hero Academia, that means the chapters written and illustrated by Kohei Horikoshi, serialized weekly in Weekly Shōnen Jump. Anime episodes faithfully following those panels—dialogue, key poses, story beats—are canon. Filler, by contrast, is anime‑original content that does not appear in the manga. Studios often insert filler to prevent the anime from overtaking the source material, to expand a battle’s choreography, or to inject comedic downtime. My Hero Academia has historically kept filler to a minimum compared to long‑running shōnen staples, but the Joint Training Arc represents a unique fusion: the anime adopted the manga’s full blueprint while adding extended fight sequences, character interactions, and breathing room that, for some viewers, muddied the line between mandatory and supplementary.

The Joint Training Arc: Setup, Participants, and Narrative Purpose

Covering chapters 194 through 217 of the manga and episodes 1–12 of the anime’s fifth season, the Joint Training Arc stages a five‑round team battle between the hero course’s two first‑year classes. The premise is simple: Aizawa and Vlad King pit their homerooms against each other to simulate the chaos of real villain encounters. Each round features a four‑person team from both 1‑A and 1‑B, with victory conditions that test capture, defense, and mobility. There are no Shiketsu students or outside schools—this is an intra‑U.A. crucible designed to sharpen quirks and foster cooperation.

Behind the spectacle, Horikoshi wove several narrative threads. With All Might’s retirement and the League of Villains growing bolder, the next generation of heroes must stop competing in isolated exam environments and start treating every bout as if lives are on the line. The Joint Training Arc provides a controlled arena where students can fail without civilian casualties, yet the psychological stakes are real: Izuku Midoriya is grappling with the legacy of One For All, Katsuki Bakugo is learning that brute force isn’t a strategy, and the often‑overlooked members of Class 1‑B get a spotlight that challenges the protagonist‑centric lens of earlier seasons.

Episode Guide and Manga Accuracy

The anime pacing dedicates about two episodes per match, with the first five bouts aligning closely with the manga’s structure. Key canon episodes include the entirety of Match 1 (Team Bakugo vs. Team Tokage), Match 2 (Team Kendo’s meticulous ambush), and Match 3 (Team Tetsutetsu’s relentless pressure). The arc’s emotional core—Midoriya’s loss of control during Match 4—is directly lifted from Horikoshi’s panels, while the aftermath in Match 5 (Monoma’s desperate gambit) remains wholly faithful. However, the adaptation also expands several action scenes. The anime injects additional choreography, extended one‑on‑one clashes, and reaction shots from classmates on the sidelines. These additions, while not present in the manga word‑for‑panel, do not contradict established lore; instead, they function as narrative padding that gives the animation team room to flex. For those following the manga first, the extra material can blur the line between required viewing and supplementary enjoyment.

Deep Dive into Canon Moments That Shaped Character Arcs

At its heart, the Joint Training Arc is a character‑focused conveyor belt of growth. Nearly every major player in Class 1‑A undergoes a noticeable shift, and Class 1‑B finally moves from background decoration to plausible threat. The following canon milestones are not simply exercises in quirk display; they permanently alter the trajectory of the series.

Midoriya’s Awakening: Blackwhip and the Quirk Singularity

Match 4, pitting Midoriya’s team against the volatile Monoma’s squad, marks the series’ first tangible glimpse of the Quirk Singularity concept. In a moment of pure desperation, Midoriya’s One For All surges and unlocks the latent quirk Blackwhip—a preexisting ability from a previous holder. Dark tendrils erupt without warning, threatening to consume both friend and foe. This is pure canon, adapted directly from chapter 212. The scene does more than introduce a new power; it confirms that One For All has evolved beyond a strength‑stockpiling quirk and will continue to manifest the spirits of past wielders. Midoriya’s horror at losing control echoes the earlier warnings that his body is a vessel housing multiple wills. The episode frames this panic with fidelity to the manga’s composition, even preserving Shinso’s critical role in quelling the rampage. In terms of future storyline setup, Blackwhip is the first domino—it foreshadows Float, Danger Sense, and the eventual full communion with the vestiges. Without this canon hook, Midoriya’s solo vigilante arc and the impending final battle against Shigaraki lose their mechanical and emotional foundation.

Bakugo’s Growth as a Team Strategist

Match 1 throws Bakugo into a role he has historically rejected: team player. His squad—featuring Jiro, Sero, and Sato—faces Class 1‑B’s Tokage, whose Lizard Tail Splitter quirk makes her a nightmare in enclosed spaces. The manga shows Bakugo devising a rapid, multi‑pronged assault that leverages each member’s abilities. The anime doubles down on Bakugo’s internal monologue, showcasing his brutal efficiency without sacrificing a shred of his trademark aggression. This arc delivers the canon achievement of a flawless 4–0 victory, but the real story is Bakugo’s gradual understanding that saving people and winning fights require coordination, not just overwhelming force. The maturity he begins to display here feeds directly into his role during the Paranormal Liberation War, where he willingly takes a lethal hit to protect Midoriya. Without the Joint Training seed, that sacrifice would ring hollow.

Class 1‑B Takes Center Stage

For much of My Hero Academia’s run, Class 1‑B operates as the shadow rival—a collection of quirky faces glimpsed during school festivals and brief interludes. The Joint Training Arc rectifies this. Characters like Itsuka Kendo, Neito Monoma, Tetsutetsu Tetsutetsu, and Kinoko Komori receive detailed combat showcases that highlight their strategic acumen. Kendo’s use of enlarged fists to disarm and disable opponents in Match 2 is a masterclass in tactical thinking, while Monoma’s Copy quirk becomes a genuine wildcard during Match 5 when he temporarily borrows One For All, only to find it empty. That moment—Kanri’s quirk Synchronicity combined with Monoma’s desperation—is fully canon and clarifies that One For All cannot simply be replicated; the vestiges deny permission. These beats not only deepen the world but also reinforce the series’ message that heroics is not a monopoly held by the so‑called main characters. The anime’s extended reaction shots from 1‑B members after each loss underline their humanity, making them feel less like NPCs and more like peers who will one day share the battlefield in the final war arc.

The Filler Factor: How the Anime Expanded the Arc

While the core structure of the Joint Training Arc is meticulously adapted, the anime team, under Studio Bones, exercised creative liberty to stretch content across an entire cour. These additions—some welcomed, others controversial—fall into two categories: extended combat and comedic relief.

Extended Combat Sequences and Visual Spectacle

Anime‑original choreography is the most visible form of filler in this arc. For instance, the duel between Iida and Honenuki during Match 3 in the manga is a brisk exchange of speed versus softening terrain. The anime expands this into a multi‑angle pursuit, adding a sequence where Iida’s Recipro Turbo nearly causes a structural collapse. Similarly, Todoroki’s flashfire techniques in Match 3 receive animated embellishments that stretch the confrontation by several minutes. These additions do not alter the outcome or introduce new narrative facts; they function as a showcase for the animation team’s fluid style. For action‑oriented viewers, these moments are a gift. For canon purists, they can disrupt the pacing, especially when the same scene essentially replays the same struggle from multiple angles. None of these extensions break the source material’s internal logic, but they do slow the arc’s momentum and occasionally dilute the tension of a well‑paced manga battle.

Comedic Interludes and Slice‑of‑Life Moments

Between matches, the anime inserts short comedy segments—Kaminari’s “Yay” outburst, Mineta’s panicked scheming, Ashido’s dance‑off encouragement. The manga contains brief quips, but the anime expands them into full‑on gag reels. One extended sequence involves Mineta attempting to “motivate” his female teammates with predictably disastrous results, a beat that halts the narrative entirely for a few minutes of slapstick. While these moments humanize the ensemble and offer the audience a breather, they rarely contribute to character growth or plot mechanics. They are classic filler: harmless but non‑essential. For fans rewatching the arc or hunting for strictly canon content, these interludes can be skipped without losing any critical information. However, they do mirror the series’ broader rhythm, reminding viewers that before the darkness of the villain arcs, My Hero Academia was a high‑school story filled with everyday absurdity.

Thematic Resonance: Teamwork, Rivalry, and the Cost of Power

The Joint Training Arc distills several of the series’ central themes. First and foremost is teamwork. The combat format forces students to combine quirks that are often incompatible. Tokoyami’s Dark Shadow and Asui’s Frog Form must synchronize in confined spaces; Todoroki’s ice and Iida’s engines demand split‑second coordination. Aizawa’s assessment after each match—constantly emphasizing synergy over individual glory—echoes All Might’s own arc, which saw the Symbol of Peace crumble because he tried to shoulder the world alone. This theme marries canon and filler seamlessly: the anime’s added banter during fights often highlights the friction that must be overcome before cooperation can click. By the final match, when Shinso joins the fray and his Brainwashing quirk becomes the lynchpin of a desperate strategy, the value of combining disparate talents is unmistakable.

Another underlying current is rivalry turned respect. Monoma’s pathological obsession with Class 1‑A is played largely for laughs throughout the series, but the Joint Training Arc reframes his hatred as a mirror of Bakugo’s early arrogance. When Monoma’s copy of One For All fails, his meltdown is not simply comedic; it is a profound moment of disillusionment. The canon beat where he realizes he cannot simply “steal” greatness underscores a core philosophy of the series: power is not transferable in a vacuum—it must be cultivated. The anime’s filler reactions from 1‑B students afterward, while not in the manga, reinforce the message that Monoma’s battle was never about defeating 1‑A but about proving his own worth.

Foreshadowing the Paranormal Liberation War

For those reading the manga ahead of the anime, the Joint Training Arc is laced with ominous foreshadowing. Blackwhip’s emergence is the most blatant signpost. All Might’s private conversations with Gran Torino after the exercise explicitly link the quirk’s volatility to the approaching threat of Shigaraki’s completed transformation. The stress of Midoriya’s uncontrollable power mirrors the chaos that will soon consume hero society. Another subtle, fully canon moment occurs when Vlad King expresses concern about the intensity of the training, remarking that the real world won’t give second chances. This line, seemingly background noise, becomes tragically literal during the Shie Hassaikai Raid and later the Jaku City battle.

The anime’s filler additions do not undercut this foreshadowing; rather, they occasionally dilute its impact. A three‑minute gag about Kaminari’s quirky eyes softens the tension built by Midoriya’s panic attack, forcing the viewer to downshift emotionally. This isn’t inherently bad—My Hero Academia has always balanced levity and gravitas—but it does mean the anime experience of the arc feels less urgent than the manga’s relentless push toward war. For viewers who watch the anime first, the subtler hints (such as Endeavor’s brief cameo on a screen during a filler break) may also be easily missed, leading some to underestimate the arc’s connective tissue to Season 6’s cataclysm.

Fan Reception and the Canon vs. Filler Debate

The Joint Training Arc arrived at a turbulent time for My Hero Academia’s anime fandom. Season 5 had already been criticized for rearranging the chronology of the My Villain Academia content, and the prolonged pacing of the training battles drew frustration from viewers accustomed to the narrative density of earlier seasons. On forums like r/BokuNoHeroAcademia, debates erupted over whether the anime “ruined” the arc or simply made it more accessible. Many manga readers pointed to the filler extensions as the primary culprit, arguing that the arc’s 12‑episode span could have been compressed into eight without losing soul. Others praised the fluid animation and the opportunity to see sidelined characters like Koda and Sero actually contribute.

Critical assessment from outlets like Crunchyroll’s seasonal reviews generally acknowledged the arc’s structural purpose while noting the pacing issues. The filler elements were not panned as outright bad, but rather as safe—studio decisions that opted for longevity over tight storytelling. Ultimately, the canon‑versus‑filler discussion around the Joint Training Arc crystallized a broader trend: as anime adaptations of ongoing manga grow more sophisticated, audiences increasingly value directorial choices that complement the source rather than pad the runtime. The arc’s mixed reception influenced Studio Bones’ approach to the following war arc, where filler was drastically reduced in favor of breakneck, manga‑faithful intensity.

Why the Joint Training Arc Matters for My Hero Academia’s Legacy

Stripping away the filler, the Joint Training Arc stands as a microcosm of My Hero Academia’s strengths. It juggles a massive cast without losing sight of individual arcs, seeds critical power developments, and reinforces the thematic bedrock of cooperation. The canon material alone offers a masterclass in group battle storytelling, where the outcome is never predetermined by simple strength but hinges on combinational strategy. The anime’s filler additions, while arguably excessive, reflect the reality of commercial adaptation: they keep the engine running so the manga can race ahead. For new viewers streaming on Funimation, the extended fights and comedic beats may enhance the experience, making the arc feel like a full season rather than a truncated bridge.

Understanding the interplay between canon and filler here is not merely an exercise in fandom pedantry; it is a lens through which to appreciate how a serialized story evolves across mediums. By isolating the Joint Training Arc’s essential beats, fans can trace clear lines from Midoriya’s first Blackwhip outburst to his final stand, from Bakugo’s tactical epiphany to his self‑sacrificial redemption, and from Class 1‑B’s debut as legitimate competitors to their eventual role in the final war. The next time someone asks whether the Joint Training Arc is “worth watching,” the answer hinges on what one seeks: a pure manga‑accurate progression or a holistic, sometimes padded, but visually vibrant adaptation. Regardless of the entry point, the arc remains an indispensable chapter in the education of future heroes—and a reminder that even in a world of quirks, growth always requires a sparring partner.