电影《密告之歌 ～警视厅监察档案～》讲述了警视厅捜査一课的刑警佐良正辉（松冈昌宏饰）在调查一桩谋杀案时，不幸失去了后辈刑警斋藤康太的故事，随后被调动到负责打击警察员工不当行为的「人事一课监察组」。在未曾痊愈的过去创伤下，他在同事们的敌视下独自完成着监察的任务，度过着孤独的日子。然而，在这样的环境中，一封密告信送到了人事一课。密告信称，他曾经的同事皆口菜子正在泄露机密数据。佐良在内心矛盾着是否洗清过去同僚的嫌疑，然而上司能马命令他展开监察，确认皆口的行动。于是，佐良开始了对皆口的调查。在此过程中，他发现了一宗未解决的谋杀案的线索，以及斋藤殉职事件的真相逐渐浮现——到底谁是背叛者？密告信背后隐藏着何种意图？在怀疑和挣扎的边缘，佐良将揭开令人震惊的真相！

《密告之歌 ～警视厅监察档案～》以悬疑刺激的情节，展现了警视厅内部的复杂权力斗争和正义追求的故事。松冈昌宏饰演的佐良是一位具有坚定正义感的刑警，不畏艰险，勇敢追求真相。故事中他不仅面对着职场压力，还要面对自己内心的挣扎，这使得他的角色更加丰满和引人深思。

影片不仅紧扣人物情感，也在故事发展中穿插了精彩的谜团和反转，让观众跟随佐良一起破解谜题、解开隐藏在背后的阴谋。同时，影片也带给观众对于正义和背叛的思考，让我们一同感受人物在这个充满矛盾与考验的监察之旅中，如何守护着最初的信念，维护着正义的使命。

The movie "Song of the Informant ~Metropolitan Police Department Surveillance File~" tells the story of the criminal policeman Zuo Liang of the Metropolitan Police Department's investigation department Masahiro (Matsuoka Masahiro) unfortunately lost the story of his junior detective Kota Saito while investigating a murder case, and was then transferred to the "Personnel Section 1 Supervision Team" responsible for cracking down on misconduct by police employees. Under the trauma of the past that has not healed, he completed the monitoring task alone under the hostility of his colleagues and spent a lonely day. However, in such an environment, a whistleblower letter was sent to the personnel department. The whistleblower letter stated that his former colleague Nanako was leaking confidential data. Zuo Liang is conflicted in his heart whether to clear the suspicion of his former colleagues, but his boss Noma ordered him to carry out surveillance to confirm Kaikou's actions. So, Zuo Liang began to investigate the mouth. In the process, he discovers clues to an unsolved murder case, and the truth about Saito's death in the line of duty gradually emerges - who is the betrayer? What kind of intention is hidden behind the whistleblower letter? On the verge of doubt and struggle, Zuo Liang will reveal the shocking truth!

"Song of the Informant ~ Metropolitan Police Department Surveillance File ~" is suspenseful and exciting The plot shows the story of the complex power struggle and the pursuit of justice within the Metropolitan Police Department. Zuo Liang, played by Masahiro Matsuoka, is a criminal policeman with a firm sense of justice who bravely pursues the truth despite hardships and dangers. In the story, he not only faces workplace pressure, but also faces his own inner struggle, which makes his role more full and thought-provoking.

The film not only closely follows the emotions of the characters, but also intersperses wonderful scenes in the development of the story. Mysteries and reversals allow the audience to follow Zuo Liang to solve the puzzles and unravel the conspiracy behind it. At the same time, the film also brings the audience to think about justice and betrayal, let us feel together how the characters guard their original beliefs and maintain the mission of justice in this monitoring journey full of contradictions and tests.