Master Group

The Tenkai Group was a pharmaceutical institution dealing in a wide range of drugs and products, including the Coldkiller X line.

Betrayal of a legacy
Main article: IS-7 Incident 

Issei Tenkai, the set heir to the Tenkai Group, chose a different path. He decided to become a pastry chef. His parents encouraged this, and as a result, Issei grew up to become a magnificent chef, largely lauded as "the world's greatest pastry chef". Despite this, Issei was still set to inherit the Tenkai Group. Among his related inheritances was the group's most guarded possession, a "recipe book" of experimental drugs not available to the general public. Among these was a recipe for a drug that could temporarily cure a disease which caused an inability to taste. As Tenkai was inflicted with a slightly less severe version of this disease, the book became very valuable to him.

However, in 2000, Tenkai decided to give away the book in a pastry making competition he was hosting. The idea of the competition was to compare contestant's works against a control made by Tenkai to see who, if anybody, would inherit the title of "world's greatest pastry chef". The Tenkai Group of course objected, but to no avail, and the contest carried on. However, the group was not to be dissuaded and sent Delicy Scone, a group member, to compete in the competition and retrieve the book.

However, two other competitors also wanted the book very badly. These were Paul Holic (who was operating under the pseudonym "Isaku Hyōdō) and Yutaka Kazami. Each had their own seperate reasons for wanting the book. Holic, despite being a famous French sculptor who sold his works for extravagant amounts of money, was in financial trouble and wished to sell the "recipe book" for a lot of money. Kazami had lost his ability to taste completely, and sought the recipe for the drug that could cure him. However, each had places in their ability that needed extensive patching. Holic, being a sculptor, had terrific design abilities but was completely unable to get the taste right. Kazami, however, made great-tasting foods that were awfully designed. As a result of this, the two agreed to collaborate; Kazami would handle all of the actual cooking while the design would be up to Holic.

However, in the finals, Holic betrayed Kazami. After the latter had made two batches of sherbet for Holic to sculpt, Holic ended their collaboration, thus giving Holic everything he needed but leaving Kazami with only his own ingredients and terrible aesthetic sense. Holic then anticipated that the desperate Kazami would try to take pictures of the recipe, and caught him doing just that. Holic threatened to expose Kazami as a thief, thus putting Kazami totally under Holic's thumb. Holic even went so far as to hit Kazami in order to prove his superiority. At this, the enraged Kazami killed Holic with a blow to the head.

Kazami decided to frame Delicy Scone for the murder, as her habit of munching on the other contestants' works had done little to endear her to him. However, Tsukasa Oyashiki discovered the body before Kazami's plot could be carried out, and thus Issei Tenkai himself was accused of the murder. Gregory Edgeworth took up Tenkai's case. While investigating, Edgeworth discovered that Scone lacked basic knowledge and that her grand finals entry was actually just a model covered in fresh cream. Edgeworth confronted Scone about this, and she was forced to divulge the fact that she was a pharmacist, and she cheated in order to get to the semifinals. However, she still hid the fact that she was involved with the Tenkai Group, fearing that the "recipe book" would be found out for what it was. She tried to make an excuse for herself by saying that she merely entered the contest to snack on the other works and that she never thought that she would make it to the semifinals. However, this was foiled by Oyashiki, who revealed that she had known Scone's true identity from the outset, and had even gone so far as to help her by informing her of Tenkai's tastes and preferences. Edgeworth subsequently learned of the drug book, and of Tenkai's disorder.

However, Edgeworth lost to prosecution legend Manfred von Karma in court. Through extensive questioning techniques, von Karma had been able to force a false confession out of Tenkai, thus ensuring a guilty verdict. However, Edgeworth was able to prove that one of von Karma's pieces of evidence had been forged. The "perfect" prosecutor was subsequently penalized, for the first and only time in his career. This would lead directly to the DL-6 Incident.

Kazami exposed at last
Main article: The Inherited Turnabout 

In 2019, 18 years after the IS-7 Incident, Miles Edgeworth, Gregory's son, and his defense attorney acquaintance Tateyuki Shigaraki paid a visit to Tenkai's mansion, which by then had been purchased by Tsukasa Oyashiki and renamed the 12 Constellations Art Gallery. They were intent on visiting an exhibit which contained a re-creation of two of Holic's sherbet sculptures, which had melted 18 years ago. However, Yutaka Kazami suddenly tumbled out of the entrance to the adjacent room, appearing unconscious. Edgeworth hurriedly ordered an evacuation of the area, recognizing the effects to be those of poison gas.

Kazami was taken immediately and treated by Delicy Scone and Oyashiki, although he would not regain conciousness for a while. Edgeworth made to investigate the cause and culprit of the gas, but he was stopped by Hakari Mikagami and Yumihiko Ichiyanagi, a rival judge and prosecutor who had arrived to do their own investigation. Ichiyanagi learned that the cause of the gas had been the mixing of two chemicals, the ordinarily harmless Normallium, which had a red tint and was often used in dyes and paints, and the toxic Fatallium, which was the active ingredient in a pesticide called Megatoxin X. Ichiyanagi introduced Larry Butz as a suspect, due to the fact that he had been carrying a red paint containing Normallium. However, Edgeworth trounced Ichiyanagi's logic by pointing out that Butz would not have had access to Fatallium, and thus he would not have had the complete palette of ingredients necessary to create the gas. Ichiyanagi then pointed to Scone as the culprit, due to the fact that she carried a bottle of Megatoxin X at all times (due to her fear of bugs), and that she was a pharmacist, so she would naturally know how the two chemicals mixed. On top of that, he added that a bottle of Megatoxin X, bearing Scone's fingerprints, had been found in the victim's pocket. He argued that Scone had tried to plant it there after creating the gas. However, Scone was able to prove that her bottle of Megatoxin X had in fact been stolen a week prior, thus beating Ichiyanagi's logic once again.

Edgeworth eventually went on to prove that it was Oyashiki who had attempted to poison Kazami, as she had been attempting revenge for the framing of Tenkai 18 years ago. Edgeworth was also able to uncover Kazami as the true culprit in the IS-7 Incident. A trapped Kazami tried to wriggle out of his predicament by pointing out that the statute of limitations on the IS-7 case had run out, meaning he could not be convicted. However, Edgeworth revealed that Tenkai had only been convicted on an accomplice to murder charge, meaning that the statute of limitations was extended for a year if the culprit could not be found. Kazami was subsequently brought to justice.