A non-human animal or a part of the same in which the function of Mipep gene is totally or partially lost in adipose tissues or the expression level of Mipep gene in adipose tissues is lowered compared to a wild type; and mesenchymal stem cells or adipocytes in which the function of Mipep gene is totally or partially lost or the expression level of Mipep gene is lowered compared to a wild type. A therapeutic or prophylactic drug that includes the mesenchymal stem cells or adipocytes or a culture supernatant thereof; and a method for preparing a mitokine mixture using the non-human cells, mesenchymal stem cells or adipocytes.