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CW: Use of gender slurs
So I would like to give a bit of clarification before starting my response to some comments given by people in response to the question regarding the gender slur, trap.
First is the mistake that the term futanari or futa means trans woman. Futanari or futa in anime and manga culture generally* aren’t trans women actually, they’re specifically “dick girls”, who are essentially cis women who have dicks instead of (or sometimes along with) a vulva. Other uses for this word refer to an intersex person who is generally seen as female in appearance for all parts except for having a penis. (Most people say that it refers to a hermaphrodite person who has a female body with a male phallus attached or their clitoris can grow to be a penis size)
Originally the term referred to someone who possessed both masculine and feminine traits, but around the 90s it started to take on the meaning we see used today, that of a cis appearing woman with a penis. In American viewing, it was originally referred to as “dick girl” and an example in older hentai animation would be La Blue Girl. Other terms used are “clit dick”, but futa or futanari have surpassed these terms in popularity in the current culture. Outside of anime and manga culture, futanari is the Japanese word for hermaphrodite. 
Outside of anime and manga culture, the word is used to refer to trans women who appear to be cisgender women at first appearance, but who have a “nasty surprise” that they are hiding under their clothes. Trans women “trap” cis men into the seeing said nasty surprise by luring them into intimate situations and then revealing their penis to the unsuspecting cis man. Examples of this can in film be seen in Naked Gun 33 1/3 in Anna Nicole Smith’s character and Ace Ventura: Pet Detective in the character Lois Einhorn played by Mary Sean Young.
It is used as a term to refer to any trans woman in casual conversation among certain groups of people, but mostly to refer to those that are considered “cis passing” by the general population. It is often used in defense against violence against trans women or a justification for the erasure of trans women, specifically claiming that trans women are actually cis men disguising themselves to traumatize other cis men or to trap cis lesbian women into a relationship only to force their penis upon them.
With that out of the way, let’s move on to the usage of the term in anime and manga culture
Trap generally refers to a cis male who looks feminine or androgynous, many times called a femme boi/boy or a lady boi/boy when the term trap is not used. A good example in one of the more “popular” animes is Haku from Naruto. They tend to be soft spoken, feminine, and have many of the typical female features you’d see in anime. They many times pretend to be a cis woman and so the trap part comes from someone, usually a man, finding out their secret and being completely horrified, shocked, or traumatized. It sometimes leads to them being accused of being perverts or being attacked. Many of these characters are voiced by either female voice actors, or a man with a higher pitched voice, which adds to the whole, “Is this person a woman?” view.
Side note: There are cases of “reverse traps” where a cis female masquerades as a cis male, with the same sort of result, and well…after the discovery things can get bad, though generally it only gets to the level of sexual assault or death in hentai or some of the nastier animes.
The reason why people try to use this as a justification of the term for trans women is because of how supposedly old the term is. The first example of this sort of character dates back to around 1949 in the manga Metropolis, and it was actually used as a plot device. (The character, Michi, was able to gender switch due to being a synthesized human) Animes like Ranma 1/2 took it a step further and made a cis male character transform when splashed with cold water into a woman, and again…used as a plot device.
From what I’ve discovered it was in the 80s when this trope really took off, but it is still used to mean pretty much the same thing as the slur we see used on trans women. The whole premise of both of the uses is that the person is a male** who is able to pass so well as a cis female, that by the time you realize that they’re in fact a man, it’s already too late. Hence the term “trap.”
Now I’m sure some anime fans will come screaming into the comments like they have before regarding this topic, telling me (an avid anime fan and someone who has been watching and enjoying anime since the early 90s and who owns a sizable collection of anime on top of subscribing to multiple streaming anime sites) that I’m completely wrong and that I know nothing of anime culture or what I’m talking about. So let me break down their typical arguments.
They tend to claim that trap is not a slur because it stands for:
- A person dressed as an alternate gender
- A person who has crossed into another gender either emotionally or physically
- Usually the best character in anime and life
(That was taken from the site 25 Anime Traps That Will Make You Question Everything)
They will try to claim that most anime “trap” characters are no more than cross dressers and thus it’s not a slur. They will bend over backwards to ignore what happens to many of the characters they label as trap. They even make AMVs (anime music videos) downplaying the trope and the issue. Honestly, just google “Dude looks like a lady amv” and look at all the examples.
They will also try to claim that because of the evidence of cross dressing or femme male characters in anime is “trans progressive” because the culture it comes from is conservative. They try to claim that these characters are embraced in the animes (usually only after the “reveal” and the shock/awe/horror occurs) and so therefore it’s not a slur. For example, check out this article, Top 20 Convincing Trap Characters in Anime.
The problem though is that many of the characters they are trying to put into the category of trap to downplay the effects of the word and the evidence of the harm of using the term that is recognized as a slur has on the transgender community are simply just femme appearing characters, not characters disguising themselves as women. We can see this in the Anime Characters Database.
If we go to the wiki devoted specifically to anime trap characters, we see a definition almost identical with what I gave above, as well as the muddling of anime culture with real life and transgender culture.
This wiki is all about anime traps and reverse traps. An anime trap is a boy who looks so convincingly like a female, that by the time you realize you have made a mistake, it’s already too late. Thus, a ‘Trap’ This term has come to refer to both anime characters and real life crossdressers [sic]/transgender people. Transversely, a ‘Reverse Trap’ refers to a girl who looks very convincingly male.
.The problem is that by trying to erase the meaning of the word, and by trying to ignore that the people most often using the word ARE using it as a slur and only going to the “but it’s Japanese anime culture” defense when called out. While this is not a comprehensive list as to all of the reasons why this is a problem, I would like to once again point out that the terms often wind up having the same use, and often wind up with the same results.
For further reading I would suggest checking out the Anime Feminist and their article which you can read here.
*I added generally because I know someone will come along and try to “actually….” this comment.
**Yes I know trans women aren’t men, so don’t start, I’m trying to explain the premise behind it all, and sadly that’s how it is set up by these people. They don’t see trans women as women, but men disguised as women.