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In her first appearance, she makes a report to Iemitsu as to the situation regarding the CEDEF and Varia. The Varia had located the base of the CEDEF, but "all 6 members" had escaped and were making their way to their current location, Vongola HQ. This implies that there are 8 or 9 members of the CEDEF in total, as Basil was in Japan and Iemitsu was not in the base when it was attacked. Next, she fought alongside Turmeric and Lal Mirch when they invaded Vongola HQ so Iemitsu could talk to and, if necessary, rescue the Vongola Boss. She and Turmeric found the censored Mosca plans and discovered that they sent one to the Varia. After they met back up with Iemitsu, the fake Vongola IX gave them enough information to realize that the real Vongola IX was in fact inside the Gola Mosca that was sent to the Varia. Unfortunately, they were too late to stop the Cloud Ring Battle.
Oregano was seen along with Basil informing Iemitsu that they had an Arcobaleno customer. Later, she confirms with Lal Mirch that she was going to fight as Colonello's (their Arcobaleno customer) representative. Oregano then arrives in Japan along with Turmeric, Basil, Lal Mirch, and Iemitsu, greeting Nana when introduced by Iemitsu. She is later eliminated on the first day of the Representative Battle of the Rainbow by Team Verde.
- As with most members of CEDEF revealed thus far, Oregano is named after a plant used in cooking, the Oregano plant.
- Oregano is the first CEDEF subordinate under Iemitsu to be introduced.