"Dekiru ka na" centers on the life of Itsuki Aoyama, a young man who struggles with self-doubt and a lack of confidence in his abilities. After a series of personal failures, Itsuki stumbles upon a mysterious notebook that grants him the power to temporarily borrow the skills and talents of others. This newfound ability allows him to excel in areas where he previously felt inadequate, from academics to sports and even creative pursuits. However, the notebook comes with a catch: its power is limited, and Itsuki must navigate the ethical dilemmas and personal consequences of relying on borrowed talents.

The narrative explores Itsuki's journey as he uses the notebook to achieve success, often at the expense of his own growth and relationships. Along the way, he encounters a diverse cast of characters, including his childhood friend Yui, who harbors unspoken feelings for him, and Riku, a rival who challenges Itsuki to confront his reliance on the notebook. As Itsuki becomes more dependent on the notebook's power, he begins to question his own identity and whether his achievements are truly his own.

The story delves into themes of self-worth, authenticity, and the pressure to succeed in a competitive society. Itsuki's internal conflict is mirrored in his interactions with others, particularly as he realizes the impact his actions have on those around him. The notebook's limitations and the moral ambiguity of its use create tension, forcing Itsuki to make difficult choices about his future and the kind of person he wants to become. The manga balances moments of humor and introspection, offering a nuanced portrayal of Itsuki's growth and the complexities of human ambition.