A chance encounter reconnects two former middle school classmates, Haru Tennoji and Manabu Taira, setting off an ambitious scheme to build a startup worth one trillion dollars. Haru is a charismatic and fearless smooth-talker who glides through any situation with confidence and bluff. Gaku is a reclusive programming prodigy whose social anxiety has left him unable to land a job, even at the nation’s leading IT conglomerate, Dragon Bank. After Haru secures a position at Dragon Bank but learns Gaku was rejected, he famously quits on his first day. He convinces Gaku to join him in building their own company from nothing, naming their venture Trillion Game.

Set in contemporary Tokyo, the story follows the duo as they navigate the ruthless startup world. The narrative often unfolds from Gaku’s perspective in the present, looking back on their unlikely rise to the top of the world’s billionaire rankings. With no capital, product, or concrete plan, their strategy relies on a simple formula: Haru’s persuasive salesmanship opens doors and secures opportunities through sheer audacity, while Gaku’s technical genius builds the products that make those promises real.

Their first major hurdle is securing funding. After a failed attempt to get an investment, they enter a high-profile security hacking tournament. Despite being disqualified for unconventional tactics, their potential attracts the attention of Kazuki Kedoin, a foul-mouthed venture capitalist with a cowboy hat who becomes their first major investor. With Kedoin’s backing, they rent a small office and begin hiring. Their first employee is Rinrin Takahashi, an excessively rigid college student working at a flower shop who is sensitive to details no one else notices. They launch Yorinuki, an online flower shop that appears to use an AI advisor, which is secretly Rinrin operating behind a VTuber avatar.

The success of Yorinuki draws the attention of Dragon Bank, which begins copying their business model. Dragon Bank is led by the greedy CEO Kazuma Kokuryu and his brilliant, arrogant daughter, Kirika Kokuryu, nicknamed Kirihime. Rather than back down, Haru escalates the conflict. Their next venture is a social game designed to compete directly with Dragon Bank’s hit title. To build it, they acquire a struggling indie game company and attempt to poach a talented but money-obsessed game designer from their rival.

As Trillion Game grows, the battle with Dragon Bank intensifies. Haru uses increasingly elaborate schemes, including fabricating a scandal to force a media alliance. He also recruits Akari Shirotora, an intense TV reporter, to build their media division. The climax of the series sees Trillion Game directly challenge Dragon Bank after refusing a buyout offer, leading to an all-out corporate war. The present-day framing device reveals that while Gaku now serves as the president of their successful company, Haru is notably absent, with the mystery of his whereabouts forming an underlying question throughout their origin story.