After socially awkward technology specialist Manabu "Gaku" Taira is saved from thugs by the outgoing Haru Tennouji, the two men find that they get along with each other well. Years later, Gaku, who is having a tough time getting a job due to his timidness, is convinced by Haru to apply for a position alongside him at Dragon Bank, one of Japan's largest IT companies.

During their interviews, the company's board director, Kirika Kokuryuu, takes an interest in Haru and Gaku's contrasting personalities. However, Gaku does not get hired by the company, leading Haru to quit the job on his first day in protest. Nevertheless, they decide to embark on an ambitious plan of making a trillion dollars.

In order for their scheme to come to fruition, Haru and Gaku start looking for potential investors, but everyone rejects their extravagant idea. In spite of that, the two soon find themselves getting an offer from Kirika—and with her investment, they might just be able to reach their goal.

Trillion Game was released on Blu-ray in four volumes from February 26, 2025, to May 28, 2025.