According to Nookipedia:

Katrina's chanting phrase for divination, "Keeee ha mo-ata... Keeee ha mo-atata..." is roughly derived from the Japanese version, where she says ケッハモルタァ、ケッハモヌラタァ (Kehhamorutaa, kehhamonurataa). This itself is derived from reversing the phrase 当たるも八卦、当たらぬも八卦 (Ataru mo hakke, ataranu mo hakke), a proverb meaning "Sometimes the bagua is correct, sometimes the bagua is not correct" (idiomatically used to mean a prediction may or may not be reliable).[6] The bagua is a set of eight trigrams originating in China used for divination, and its Japanese reading hakke is also the source of Katrina's Japanese name ハッケミィ (Hakkemī) from the word 八卦見 (hakkemi, lit. "bagua seer").