Mitsuru Toyama is an unaging alien that came to Japan 400 years ago. 3 months before finally heading home, vain actress Tsubaki Sasahara moves in next…
University teacher Mitsuru Toyama hasn't aged a day since coming to Earth 400 years ago. 3 months before finally heading home, actress Tsubaki Sasahara moves in next door. Her loud midnight singing disturbs Mitsuru, who has 7 times better hearing than humans. When he goes to confront her, he realizes just how hurt she's been. Meanwhile, Tsubaki's childhood friend Hiroya Uwajima proposes to her.
Mitsuru sees an ominous dream of a stiletto floating in the water. That night, Tsubaki crashes into his room, drunk. He finds her purse and discovers an old photo of her, looking exactly like the girl he saved 400 years ago. He had saved another girl 12 years ago with the same face, and realizes that it was Tsubaki. He sees her wearing the stiletto from his dream, and warns her never to wear them.
After saving Tsubaki, Mitsuru hears a disturbing conversation between Masaya Uwajima and his secretary. Next morning, Reiko Bando is found dead in the sea. A suicide note is found, and witnesses say she and Tsubaki had been quarrelling. The media blames Tsubaki for Reiko's death. To hide from reporters, she escapes to Mitsuru's room. There, she finds his diary titled "My Last 3 Months on Earth."
While sheltering Tsubaki, Mitsuru's friend Seiichiro Kurachi comes to visit. The reporters leave, and Tsubaki goes home, but she's fired due to the gossip concerning Reiko's death. Meanwhile, Masaya discovers that Tsubaki has the USB containing his dark secret, and comes for it. Mitsuru saves her and finds a camera hidden in a gift from a "fan." Hiroya once again proposes to the desolate Tsubaki.
Tsubaki's mother and brother come visit to find Tsubaki and Mitsuru quarrelling. She introduces him as her new manager. Mitsuru hears that Tsubaki had rejected Hiroya's offer and is relieved. Later, Tsubaki is in shock to find out Yukino had taken over her lead role. They meet the next day, and she's hurt by Yukino's words. As she leaves, Mitsuru spots a man dropping a vase on her and saves her.
Mitsuru saves Tsubaki from falling off a cliff using teleportation. Tsubaki swears she saw him, but he claims she couldn't have. Meanwhile, Masaya presumes that Mitsuru has the USB and wants it back. Ono and Natsume investigate Reiko's death and find a suicide note in one of her shows, the exact one she'd left behind. They realize the suicide was staged, and Tsubaki's suspicions are cleared.
