Bak Chan's Capriccio (バク．チャン狂想曲(カプリッチオ), Baku.-Chan kyōsōkyoku (kapurichoo)) is the third chapter in the first volume of D.Gray-Man: Reverse novels.This chapter mainly focuses on Bak Chang the Branch Head of Asian Branch as he tries to find how Komui Lee was elected as European Branch Head and not him. He calls for a 'The Tea of Truth' which when drunk causes the drinker to reveal his/her concealed thoughts.
The chapter begins when Bak Chan arrives at the European Branch HQ for General Meeting. The visit reawakens his long hatred for Komui Lee who he thinks is not worthy of running HQ. While wandering HQ, Bak meets various organization members including Yu Kanda and Lenalee.
Sammo Han Won brings the teabags that Bak asked for. Won informs Bak that as there wasn't much time for the preparation so they managed to produce only three teabags with short efficacy. Bak tells Won how important this 'Tea of Truth' is as it reveals true motives and intentions of the drinker. Bak informs Won that he is planning on making Komui drink it so he can judge his motives and kick him out of the branch.
The duo proceeds to the cafeteria to prepare the tea but is ultimately interrupted by Jeryy and his fellow chefs. They allow Bak to make the tea but drink it themselves as a 'treat' from Bak. Bak decides to use this scenario to his advantage and test the efficacy of the tea. It is revealed that the drinker gets red when the tea is in effect and starts speaking the truth inadvertently. Jeryy and the other chefs start openly wondering about whether Bak has a bald spot because his hair is too thin and is always covered with a beret. Won, who is forced to drink the tea, also adds comments about Bak's narcissism. Bak gets infuriated by their comments but is content to know that the 'Tea of truth' is actually effectual.
Bak leaves the cafeteria and swears that he'll make sure that he protects the final two teabags and make Komui drink the tea. While he is deciding this, he meets Lavi who carefreely informs him about a party held by Komui himself. Bak wonders why he isn't invited and gets more frustrated. He meets Lenalee again and offers her to carry some of her work to her brother's office. When they arrive at the office, Bak informs Komui Lee that he has brought a 'special treat' for him from China. Komui cordially accepts the offer and Lenalee helps prepare the tea. But before tea could be served to Komui, Reever comes in and tries to drink it. Bak tries to stop Reever from drinking which causes the tea to spill on Lenalee. Lenalee doesn't get burns because of her uniform but she leaves to change and so does Reever after a brief apology.
Alone with Komui with one last tea bag left, Bak sees this as his sole chance to suceed in his plan. He makes the tea again and serves it. Komui refuses to drink while Bak is looking at him so intently, so Bak turns around and lets Komui drink it in peace. Bak starts interrogating Komui about his work and motives but it is in vain because Komui doesn't really reveal anything incriminating. Before the tea's effect could come to an end, Bak decides to ask Komui what he thinks of him. Bak is shocked to find out that Komui extols him. In return Komui asks Bak if he thinks it's right for him to be head officer. Bak assures him of his position and tells Komui everyone is counting on him. When the discussion comes to an end, Bak finds Komui staring at him in a peculiar way and asks about it. Komui informs Bak that he knows that Bak was trying to flirt with Lenalee while they were preparing the tea and warns him to keep his distance from her. Bak is startled and says that Lenalee should have freedom to love anyone she likes. At the mention of love, Komui goes berserk and pulls out a hidden machine gun from underneath his desk. He starts shooting around and declares that if Lenalee disappears he'll kill everyone and then himself. After trying to get Komui to stop shooting and failing, Bak makes it for the door.
Outside, he meets Lenalee again who invites him to come with her to the cafeteria. When they arrive at the cafeteria, Bak is surprised to find a birthday party and an enormous cake with the words 'Happy Birthday Bak-chan!' Lenalee tells Bak that he looked unhappy recently so Komui suggested arranging a birthday party for him. While everyone is planning to toast champagne, Bak informs the crowd that his birthday is on November 11, not today, January 4. Komui walks in then and apologizes for making the mistake as he thought Bak's birthday was 'four of one'. The birthday party proceeds normally until Komui and the science department present their gift to Bak which is a tonic for hair growth. Komui tells Bak that he always seemed so concerned about his hair, looking in the mirror and adjusting his beret frequently, that's why the science department made the tonic for him. Bak concludes that Komui must have been the one who spread the rumor that Bak has a bald spot. Bak is forced to accept the gift and apply it right then, as everyone was looking at him expectantly. Soon after he finishes applying the strange hair tonic, Bak finds his hair growing abnormally fast. The science department informs him that the effect will stay for 24 hours and if the hair is cut it will grow again till then. Bak gets frustrated and embarrassed for having to attend the upcoming general meeting with long hair and wonders if Komui Lee knew about his plans to use the tea on him from the very beginning. Bak curses Komui Lee and swears to replace him in the Black Order someday.
Bak Chan's itching problem when nervous is briefly mentioned in this chapter.