The Promised Neverland's first season set a high standard with its gripping plot and suspenseful atmosphere. However, the second season's rushed pacing and exclusion of key manga content led to widespread disappointment, tarnishing the series' overall impact.

Tokyo Ghoul started strong, enticing audiences with its dark, complex world. However, as the anime strayed further from its manga roots, fans were dismayed by the rushed and confusing narrative, ultimately feeling let down by the series' inconsistency and lacklustre adaptation.

Ouran High School Host Club charmed viewers with its humour and heartwarming moments, yet the series ended abruptly without a proper conclusion. Fans were left yearning for more, disappointed by the lack of a second season that could have wrapped up the story's loose ends.

One Piece stands as a monumental achievement in anime, but its sheer length demands an unwavering commitment. With over 1,000 episodes and counting, many viewers regret starting a series they feel they'll never have the time or patience to see through to the end.

Soul Eater delivered an exciting blend of action and supernatural elements, yet its finale failed to satisfy. The abrupt and inconclusive ending undermined the series' themes, leaving fans disappointed and feeling that the story's potential had been wasted.

Attack on Titan captivated fans with its intense, unpredictable storyline, but significant changes in the narrative arc sparked controversy. The deviation from certain expectations and the introduction of new plot twists left some viewers feeling betrayed and dissatisfied.

Clannad is renowned for its ability to evoke deep emotional responses, often leaving viewers in tears. While this speaks to its powerful storytelling, the intense emotional journey can be overwhelming, causing some to regret the heartbreak they experienced throughout the series.

Madoka Magica subverted the magical girl genre with its dark themes and unexpected twists. While innovative, its departure from traditional tropes left some fans of the genre feeling alienated and regretful for venturing into a series that challenged their expectations.

Nana's relatable characters and realistic portrayal of relationships drew fans in, but its abrupt hiatus left the story incomplete. The unresolved ending left viewers frustrated and regretful, longing for closure that never came.

Assassination Classroom provided a unique blend of comedy, action, and heartfelt moments, but its ending left viewers emotionally shattered. The unexpected and bittersweet conclusion, while impactful, led many to regret the emotional investment they had made in the series.