Hassak is a character from the Pokémon Horizons: The Series who holds the dual roles of a member of the Paldea region's Elite Four and an art teacher at Naranja Academy. His background reveals he is the descendant of a long line of Dragon-type Pokémon trainers from an unnamed faraway region, though he chose to leave his family home in his youth to pursue a dream of making music. This path eventually led him to Paldea, where he became both a respected member of the Pokémon League and an instructor.

In terms of personality, Hassak is characterized by a gentle and encouraging nature, particularly towards his students. He is deeply invested in the growth and progress of others, and an extremely emotional individual who frequently bursts into tears of joy when witnessing admirable character development or effort from young trainers. This emotional expressiveness is a core part of his identity, as he cries openly during moments of pride and appreciation.

Hassak's role within the story of Pokémon Horizons begins when he first appears alongside fellow Elite Four member Rika to welcome the protagonists Liko, Roy, and Dot to Naranja Academy. He becomes involved in their development as trainers through various events. During the annual Artazon Art Festival, Hassak assists with preparations and discovers that Liko is the daughter of his acquaintance, Alex. He then introduces the young heroes to the Artazon Gym Leader, Brassius, who is an old friend of his. As part of the young trainers' Terastal training, Hassak participates in a Tag Battle, teaming up to face Roy and Brassius and emerging victorious. He later serves as a referee for a significant battle against Geeta, the Top Champion of Paldea.

Hassak has several key relationships that inform his character and actions. His friendship with Brassius is particularly important, as Hassak previously mentored the gym leader during a period of artistic insecurity. As a teacher, he is shown to be proud and caring towards students like Liko, Roy, and Dot, evaluating their artistic works and praising their battling progress. He also interacts regularly with other members of the Paldea League, including Nemona and the other Elite Four members. His known Pokémon include Dragon-type creatures such as Gible, Flapple, and Baxcalibur, which he has used in showcase battles. Throughout the series, Hassak demonstrates his notable abilities both as a skilled Dragon-type trainer in high-level Elite Four battles and as an insightful art instructor who can recognize and nurture creative potential in his students.