The 2019 New Years' issue.
Oh! Cult! is an occult magazine read by Maya Fey and Pearl Fey. Notably, the 2019 New Years' issue, which was issued around Feb. 7, advertised the Hazakura Temple and its spiritual training, featuring a picture showing Bikini and Iris, two nuns at the temple. Maya and Pearl showed this issue to Phoenix Wright, who declined at first but then saw Iris, who looked exactly like Dahlia Hawthorne, and agreed to go with them.
The trip to Hazakura Temple resulted in a murder. On Feb. 9, during the subsequent trial, the presiding judge noted that he, too, had read the New Years' issue to learn more about the Kurain Channeling Technique, which was a major factor in the case. Oh! Cult! is a pun on "occult".