The Dark Lord of the Sith, known as Darth Vader, kept a personal journal with a green cover. This Vader's diary served as a repository for his innermost thoughts regarding his daily existence. He documented everything from his excitement over a new helmet to his anxieties about revealing his true identity to his son, Luke Skywalker. A significant entry details Vader's profound disappointment when the stormtroopers under his command failed to acknowledge his birthday, plunging him into a state of depression.
Between the years of 0 ABY and 3 ABY, a stormtrooper named Bob pilfered the diary from Vader's private chambers and shared it with his comrade, Kjazhed-Uhl. During a midday respite, the two soldiers perused the diary, offering commentary on its contents and gaining insights into previously unknown aspects of Vader's character. After reading about his neglected birthday, the stormtroopers developed a newfound sense of empathy for the Sith Lord, leading one of them to secretly wish Vader a happy birthday.
The Dark Lord of the Sith, Darth Vader, possessed a diary. This book, identified with his name on the cover, featured a green exterior and a dark spine. Inside, his reflections on various occurrences in his day-to-day life were chronicled. One entry detailed his reaction to acquiring a new helmet, which he deemed superior in fit and more intimidating in appearance. Vader also noted a lack of time for writing due to an impending morning meeting, a prospect he disliked as it interfered with his desire to engage in malevolent activities. He also mentioned experiencing "nitemares" (nightmares). Elsewhere, the Sith Lord expressed his apprehension regarding an upcoming encounter with his son, Luke Skywalker, who remained unaware of his true parentage.

Vader expressed uncertainty about conveying the truth and feared his son's disbelief and anger upon learning that his nemesis was his father. He also contemplated the difficulties his son must have faced growing up without a father, mirroring his own experience. Vader, averse to rejection, hoped to avoid having to kill Skywalker and envisioned them uniting to rule the galaxy. He also acknowledged his pessimistic nature and the need for greater confidence. A subsequent page featured Vader's illustrations depicting violent acts with his lightsaber against Imperial officers and aliens. Further pages contained descriptions of Vader's hatred, atrocities he had committed, and an experience with an incurable rash.

A significant portion of the diary revealed Vader's mistaken expectation of a surprise birthday party organized by his stormtroopers. This belief stemmed from a peculiar atmosphere he sensed during a lineup as his birthday approached, initially interpreted as a potential mutiny, though he dismissed it as improbable. He recalled the absence of birthday celebrations in previous years, attributing it to the replacement of those stormtroopers. Vader mentioned dropping hints about desired gifts, such as a scooter or an electric toothbrush. The following morning, on his birthday, Vader recorded the events. He had been summoned to a meeting, anticipating a surprise, but found only General Chymoelaan present.
Vader searched for hidden individuals, but found none. En route back to his quarters, he overheard a party, celebrating the birthday of a stormtrooper who shared his special day. Vader resolved to eliminate the stormtrooper. Upon entering the room, he was met with stunned silence from the stormtroopers. Feeling excluded, Vader retreated to his quarters. The Sith attempted to find solace in his accomplishments but was unable to suppress his depression. He sought sleep, but three days of sleeplessness and a diet consisting solely of cheese curls for the past eighteen hours led to a decline in his mental state, culminating in an attempt to contact his deceased mother. Vader lost consciousness during the night and felt ashamed upon awakening. He wrote in the diary that discovery would necessitate the elimination of the discoverer.

Darth Vader documented his daily life in his diary, concealing it beneath a stack of magazines in his quarters. Sometime between 0 ABY and 3 ABY, stormtrooper Bob stumbled upon Vader's diary while removing a deceased body. He intended to read it during a weekend in Vader's absence, considering it a unique opportunity. During a lunch break, Bob encountered fellow stormtrooper Kjazhed-Uhl, sharing his discovery. Both stormtroopers decided to begin reading, starting with the entry about his new helmet. After debating the accuracy of Vader's spelling of "nightmare" as "nitemare," they skipped ahead, finding the passage where the Sith Lord reflected on his feelings for his son.
The stormtroopers deemed Vader's illustrations to be of subpar quality. Seeking Vader's opinions of them, Bob and Kjazhed-Uhl advanced to the section concerning them, discovering his reaction to his forgotten birthday. Reading the diary gave both stormtroopers a deeper understanding of Vader, which they felt explained his tortured existence. Bob suggested that Vader needed a creative outlet like painting or dancing, while Kjazhed-Uhl believed that directly addressing his issues would be the solution. Later, after Vader called an emergency meeting to find an intruder, one of the stormtroopers quietly wished the Sith a happy birthday, prompting him to pause and glance back at the trooper.
Vader's diary was featured in "Lunch Break," a non-canon comic written and illustrated by Jonathan Adams. It was published in Star Wars Tales' sixteenth issue on June 25, 2003 by Dark Horse Comics.