"Dengeki Daisy" is a manga series that blends romance, comedy, and drama, centering on the lives of its two main characters, Teru Kurebayashi and Tasuku Kurosaki. Teru is a high school student who, after the death of her older brother Soichiro, is left alone and struggling financially. Before his death, Soichiro entrusted Teru to a mysterious figure known only as "Daisy," who communicates with her through a cell phone he left behind. Daisy becomes Teru's emotional support, offering advice and encouragement through text messages, though his true identity remains unknown.

Tasuku Kurosaki, the school's janitor, is a gruff and seemingly indifferent man who often crosses paths with Teru. Despite his rough exterior, Kurosaki secretly cares for Teru and is revealed to be Daisy, the person she has been confiding in. Kurosaki was a close friend of Soichiro and promised to look after Teru, though he hides his identity to maintain a sense of distance and protect her from his troubled past. As the story progresses, Teru begins to suspect Kurosaki's connection to Daisy, leading to a gradual unraveling of their relationship.

The narrative explores themes of loss, trust, and redemption as Teru and Kurosaki navigate their evolving bond. Teru's cheerful and determined personality contrasts with Kurosaki's guarded demeanor, creating a dynamic interplay between the characters. The series also delves into Kurosaki's past, revealing his involvement in a hacking incident that led to personal and professional consequences, adding layers of complexity to his character.

Secondary characters, such as Riko Onizuka, Teru's best friend, and Akira Dojima, a teacher with a mysterious connection to Kurosaki, contribute to the story's depth. The plot intertwines moments of lighthearted humor with emotional tension, particularly as Teru and Kurosaki confront their feelings for each other while dealing with external challenges, including threats from individuals connected to Kurosaki's past.

"Dengeki Daisy" balances its romantic core with elements of mystery and action, creating a multifaceted narrative that keeps readers engaged. The gradual development of Teru and Kurosaki's relationship, combined with the exploration of their individual struggles, forms the heart of the story, making it a compelling blend of genres.