Sota Yukimura (Hokuto Matsumura) works in the brand division of the cosmetics company "Nose Cosmetics" and has harbored an unwavering, unrequited love for his boss—and first love—Mariko Nose (Sae Okazaki) for 25 years. Unaware of Sota's feelings, Mariko finds herself unexpectedly weeping in his arms, reminded of her beloved late mother. She begins to take increasing notice of Sota, who always appears to lend a hand whenever she is in trouble. As the police begin to eye Sota as a murder suspect, he remains determined to protect Mariko's smile and continues to investigate the truth behind the attempted kidnapping she suffered 25 years ago—an event that left her deeply traumatized. Sota discovers a connection between the serial kidnapper who attacked Mariko, Satoru Hatano (Yoji Tanaka), and her father, Ginjiro Nose (Ken Ishiguro)—the president of Nose Cosmetics. Suspecting Ginjiro might have been involved in the incident, Sota attempts to uncover the president's secrets. Meanwhile, Ginjiro's secretary, Gota Asai (Atom Shukugawa), is suddenly replaced. When Mariko worries about Asai's abrupt disappearance from the office, Ginjiro dismisses it, claiming Asai is simply taking some time off... That night, Sota sneaks into the empty office and searches through Asai's desk, looking for clues to expose Ginjiro's secrets—but what he finds... What exactly has happened to the missing Asai? Furthermore, will Mariko finally discover Sota's long-held secret love...?

Sota Yukimura (Hokuto Matsumura) works in the secondary brand division of the cosmetics company "Nose Cosmetics." He goes on a Ferris wheel date with his boss, Mariko Nose (Sae Okazaki)—whom he has secretly loved for 25 years—and spends a dreamlike time with her... but that happiness is short-lived. His secret is exposed: he had attended the same junior high and high schools as Mariko all along. Upon realizing that Sota had been watching her from nearby for so long, Mariko is unable to hide her bewilderment and leaves him behind to go home... "It's over... my 25-year-long love..." Sota is devastated, believing Mariko now hates him... Meanwhile, the police—led by Detective Taisuke Sakura (Tetsuji Tamayama) of the First Investigation Division, who suspects Sota of murder—uncover the fact that Sota and Mariko attended the same schools and begin to speculate on a motive. They suspect that Sota, harboring an intense obsession with Mariko, may have killed Tsuyoshi Tateiwa (Tomomi Maruyama), a colleague who was vying with Mariko for a position within the company... Furthermore, Taisuke visits the detective agency Tateiwa had hired and obtains crucial documents that hold the key to the events leading up to Tateiwa's murder... Amidst this, Sota—determined to protect Mariko's happiness—grows suspicious regarding the accidental death of Mariko's biological mother, Kyoko, and goes to meet a certain individual... And finally, the true culprit behind Tateiwa's murder is revealed! Just who is the killer...!?