The Road to Sirius.

Tatsumura Yusuke, Toho Advertising's deputy sales manager was a childhood friend of Akiko and Katsuya. In fact, there is a secret that cannot be divulged about the relationship between Akiko and her father and the truth behind his death between these three people. They don't contact each other after they grow up but 25 years later, that secret comes back to Akiko in an extortion letter. Meanwhile, Tatsumura's division suddenly competes in a big project with a budget of 1.8 billion yen. Tatsumura works towards a successful pitch with Tachibana, Hirano, and Totsuka but interference within the company from envious parties and a heated contest with a rival firm remains. Then Tatsumura learns that there is a link between this project and that secret from his past...