A "genderswap" refers to the almost magical version of a sex change, wherein a character of one sex turns into one of the other sex without any medical involvement.
This tag can also apply to an image of a character of one sex depicted as one of the opposite sex (e.g. a male version of a female character or vice versa). May also apply to male-to-futanari, but since futanari is not wholly female, female-to-futanari may also qualify. A being with no sex depicted as any of these may technically count.
This tag can also be applied to an otoko no ko if the character is given female traits such as the presence of actual cleavage or the obvious absence of a bulge at the crotch. For reverse traps, the absence of cleavage or presence of a bulge applies.
If a character is genderswapped often enough, the genderswapped version may be given its own name. For male-to-female genderswaps, this is often the normal character's name with "ko" appended to it. (子 "Ko" meaning "child" is a common ending for Japanese girls' names.) For female-to-male genderswaps, "o" is sometimes added.
Known in Internet circles as Rule 63, wherein there is a female or male version of any given male or female character, respectively.
Notes:
If the person has only swapped bodies with another from the opposite sex, but the body itself has not changed, then use personality switch instead.
The "女体化" tag may also on occasion be used to describe female personification, rather than a genderswap.
