Please answer the following question: I am a movie director and I just received the following movie plot. Could you help me answer this question? If not, let me know by writing "Not answerable". Plot title: You Only Live Twice Movie plot: An American NASA spacecraft is hijacked from orbit by an unidentified spacecraft. The U.S. suspect it to be the work of the Soviets, but the British suspect Japanese involvement since the spacecraft landed in the Sea of Japan. To investigate, MI6 operative James Bond is sent to Tokyo after faking his own death in Hong Kong and being buried at sea from the HMSTenby(F65). Upon his arrival, Bond is contacted by Aki, assistant to the Japanese secret service leader Tiger Tanaka while watching sumo. Aki introduces Bond to local MI6 operative Dikko Henderson. Henderson claims to have critical evidence about the rogue craft, but is killed before he can elaborate. Bond chases and kills the assailant, taking the assailant's clothing as a disguise and escapes in the getaway car, which takes him to Osato Chemicals. Once there, Bond subdues the driver and breaks into the office safe of president Mr. Osato. After stealing documents, Bond is pursued by armed security, but is rescued by Aki, who flees to a secluded subway station. Bond chases her, but falls down a trap door leading to Tanaka's office. The stolen documents are examined and found to include a photograph of the cargo ship Ning-Po with a microdot message saying the tourist who took the photo was killed as a security precaution. Bond goes to Osato Chemicals to meet Mr. Osato himself, masquerading as a potential new buyer. Osato humours Bond but, after their meeting, orders his secretary, Helga Brandt, to have him killed. Outside the building, assassins open fire on Bond before Aki rescues him again. Bond and Aki drive to Kobe, where the Ning-Po is docked. They investigate the company's dock facilities and discover that the ship was delivering elements for rocket fuel. They are discovered, but Bond eludes the henchmen until Aki gets away; however, Bond himself is captured and knocked out. He wakes, tied up in SPECTRE operative Helga Brandt's cabin on the Ning-Po. She interrogates Bond, but he thinks he has managed to bribe his way to freedom. Brandt then flies... My question: Who is the the Japanese secret service leader?
A:
Tiger Tanaka