This tag is a subset of the genderswap tag, and it indicates which kind of change it is, namely male-to-female (mtf). The spear counterpart to this tag is genderswap (ftm), i.e. female-to-male, which can be used in conjunction with this tag to indicate that both changes are present.
Note: Please be aware that the "女体化" tag may also on occasion be used to describe female personification, rather than a genderswap.
