Sikerei is often referred to as the doctor of the Mentawai people because he has the ability to treat the community in the traditional way from the leaves obtained in the forest, to distinguish sikerei from ordinary people Sikerei has tattoos on his body that symbolize the level of strata. Mentawai tattoo (titi) as one of the oldest tattoos in the world, so it is not surprising that many anthropologists around the world are studying various immaterial cultures in this region.

Tattoo (tattoo). A tattoo is a mark made by inserting pigment into the skin. In technical terms, a diagram is the implantation of micropigments. Diagrams can be made against human or animal skin. Diagrams in humans are a form of body modification, while diagrams in animals are generally used as identification. Tattoo comes from Tahiti, tatu which means is a sign. The tattoo in Mentawai language is titi. There is a slight difference in the sound of the origin of the word tattoo. While the function of tattoos in general is usually to signify someone who comes from a certain community or social class or to beautify themselves. Especially for the Mentawai tribe, tattoos have more than just social signs in their community. For them, tattoos or titi are a reflection of the close relationship between the Mentawai community and the surrounding environment.

Titi Mentawai is usually used by men and women in a village community. The man or woman who will wear titi is usually mature, has skills (hunting) and is well established in his social life, such as some cattle and trees owned by the person. If someone has been judged worthy to wear titi then all relatives and parents. The interesting thing about this titi phenomenon is the role of village shamans known as Sikerei. Sikerei have a very high social function because they are considered leaders of the community and also leaders of their beliefs, especially during ceremonies.

Life policies and lifecycles are always associated with ceremonies. This can be seen from birth, marriage and death ceremonies, house-making ceremonies and including titi-making ceremonies for a person. Someone who has used titi will definitely become or he is a Sikerei. Sikerei will lead a preparatory ceremony for the granting of titi to someone who is from Mentawai or not even from Mentawai. This ceremony aims to ask permission from the spirits of their ancestors so that at the time of making titi will run smoothly and the person who is given titi is always given health.