Chapter One: That Man – Is He Trustworthy?

That Man – Is He Trustworthy? (その男, 不審につき, Sono Otoko, Fushin Nitsuki) is the first chapter of Dengeki Daisy, published in volume one of the series.

Synopsis
Shortly before Soichiro Kurebayashi dies of illness, he tells his younger sister Teru that DAISY, an unknown person to her, will always be able to support her when she needs help and gives her a cell phone that will connect her to him. Despite her initial reservations, Teru soon accepts DAISY as a pillar of strength and she confides in him with daily messages.

However, Teru and her friend Kiyoshi Hasegawa must endure the bullying of the Student Council, led by the president, Rena Ichinose, because they are scholarship students, so they are not wealthy. Though Teru quickly shows she is not afraid of them, the Student Council is driven away by a series of mysteriously thrown tennis balls. To thank their anonymous benefactor, Teru tries to throw a tennis ball back - only to accidentally break a window. Kiyoshi leads Teru away in hopes that they will not be caught; unknown to them, someone has seen the entire incident.

The mysterious person confronts the students in Teru's class and attempts to frighten them into revealing who broke the window. Though her friends try to protect her, Teru feels obligated to tell the truth. The man, revealed to be the school janitor Tasuku Kurosaki, forcibly takes Teru away... to become his personal servant until she can pay for the broken window. An antagonistic relationship develops between the two as Teru is forced to do most of Kurosaki's job while he slacks off. However, her time with Kurosaki allows her to learn that Rena is in an illicit relationship with the school's information technology teacher, Tetsuya Arai, and the Student Council stops bullying her after DAISY suddenly sends them a message threatening them if they should bother Teru again.

Kurosaki notices that Teru is unwilling to openly ask DAISY for help, despite the fact she seems to trust him; she reveals that she does not want to take advantage of DAISY's kindness. When Rena reveals that she suspects Arai has been stealing funds from the Student Council and desperately asks Teru for help, Teru gives in and asks DAISY to save them from Arai, who is quickly exposed thanks to DAISY's expert hacking skills.

After hearing DAISY's voice for the first time, Teru suspects that he may be Kurosaki. Unknown to Teru, Kurosaki is indeed DAISY, but when she confronts him, he quickly dismisses the idea, much to Teru's apparent relief.