Joker Game (Part 1) (ジョーカー・ゲーム（前編) ) is the series premier of Joker Game. The episode introduces the mysterious, clandestine organization known as the "D-Agency"
The episode begins In medias res with a group military police conducting a raid on an American's house, much to the American's anger. A member of the policemen makes a wager, saying the captain conducting the raid will commit hara-kiri if they do not find evidence.
In 1937, with the Second World War looming on the horizon, the Imperial Japanese Army forms a clandestine spy organization known as the "D-Agency". The D-Agency goes through an arduous recruitment process and candidates are kept in utmost secrecy as they are trained in the sciences, foreign languages, and lockpicking.
Lt. Sakuma is sent by General Staff Headquarters as a liaison to report on D-Agency. He meets with Lt. Col Yuuki, the founder and leader of the D-Agency. Sakuma bows to Yuuki, amused, Yuuki responds "Are you stupid? Who bows wearing a business suit?" Shaken by the reception from Yuuki, Sakuma tells Yuuki about his task investigating D-Agency. Yuuki retorts that "you're the spy sent by General Staff Headquarters?". Sakuma, offended, says that spies are "cowards".
Being a graduate of a military college, Sakuma is surprised to the mentality of the D-Agency, including the fact that they seemingly have no order of command (except Yuuki's leadership position) and the members have fake identities. Late one night, as Sakuma was getting a pitcher of water, he comes across the members of the D-Agency playing poker. Miyoshi, a member of D-Agency, invites Sakuma to play along. Sakuma agrees, but loses. As Sakuma shrugs of his loss and prepares to leave, Odagiri, a D-Agency member that was not playing poker, reveals to Sakuma that he was peeking at his cards and signaling the others. It turns out that they were actually not playing poker at all, but rather a completely different game. Miyohsi explains this game as "Joker Game", the goal of which is to form alliances and trick others into having an enemy spy joining your side.
Sakuma, disgusted and confused, scolds the members when Yuuki comes in the room and hears about Sakuma's grievances. Yuuki comments on the nature of international politics, now ever prevalent with espionage, that spying is essential, particularly citing an international disarmament summit in which the US usurped the Japanese. Yuuki asks what Sakuma would do in a situation when he was captured. Being from the Army, Sakuma replies that he would either "kill his enemies" or "die with honor". The members of D-Agency and Yuuki laugh, saying that killing your enemies or yourself is the worst you can do as a spy, as the police will inevitably be involved. Sakuma defensively says he'll see his comrades at the other side, but Yuuki asks "what if you don't?" Sakuma, indoctrinated with nationalism, is surprised by this question. Yuuki asks Miyoshi on his opinion and Miyoshi says it's mere "tautology", Kaminaga, another member of D-Agency, adds that if "Japan lost the war, the people would promptly take there faith and put it in the antithesis of the original belief". Sakuma is shocked at hearing the slightest possibly that Japan might lose the war. Yuuki says the impetus for D-Agency is not for money, honor, or patriotism, but the confidence in their skill to constantly adapt to any situation. Sakuma leaves the poker game, astonished by the coldness of the D-Agency.
Sakuma is ordered by Mutou, a colonel from General Staff Headquarters, to go with D-Agency and find evidence proving John Gordon, an American arms businessman and a "japanophile", as a spy. As Sakuma reports to Yuuki these orders, Yuuki comments that these "orders are stupid", saying that a spy that is caught is finished, and they will escape if they are left alone. Nonetheless, Sakuma insists that "orders are orders" and Yuuki briefs Miyoshi on the mission. Miyoshi says to disguise D-Agency as a military police unit and asks Sakuma to act as captain and interpreter.
When the D-Agency arrives, Gordon is angered by their arrival, but Miyoshi makes a deal with Gordon that the captain will commit hara-kiri if they do not find evidence. Sakuma asks what Miyoshi said to Gordon, to which Miyoshi "replies that "you will cut your own stomach if we can't find evidence". As the D-Agency search Gordon's home, Gordon angrily explains to Sakuma that this is the second time the military police searched his home. Sakuma is astonished by this revelation and realizes that the D-Agency will not find the evidence. As the D-Agency report no evidence seen, Sakuma comes to the point where he has no choice but to commit hara-kiri, knowing that he might've pulled the joker in the "Joker Game". The episode cuts to black, and the situation is left at a cliffhanger.