The so-called tattoo involves members on the periphery of the Red Butterfly who have an 'R' letter tattooed on their bodies.
The majority have it on their arms. The purpose has been mentioned before: it's to ensure that members of the Red Butterfly can confirm each other's identities.
This is already no secret.
However, Xiaofan was indeed a bit puzzled. Why hasn't such a strict matter been changed after being exposed? If Red Butterfly's opponents, say himself or people from Yanhuang Soul, use such tattoos to make contact, wouldn't it be easier to understand Red Butterfly's movements?
However, Xiaofan soon discovered that while peripheral members have such tattoos, there are only a few assassins within the Red Butterfly who have them.
Upon inquiry, Xiaofan learned that when contribution to the organization reaches a certain level, one becomes an internal member, and then the tattoo is washed off.
