Kyriaki (キリアキ kiriaki) is the first strain of GUILT encountered in Under the Knife, Second Opinion and Under the Knife 2. They use their sharp tail to create lacerations. Upon opening a patient infected with Kyriaki, lacerations in the organs will be found; these must be healed to make the Kyriaki emerge. If left untreated, the Kyriaki's host goes into cardiac arrest and dies. After surviving a Kyriaki infection, the host may contract Post-Kyriaki.