A recent interview with a popular Japanese manga creator provides insights into how the term “Asperger” is both little understood in Japan, and at the same time widely appropriated by Japanese internet subculture.
In early April, in an interview  with the Japan-based pop culture website Niconico , popular manga creator Yamada Reiji (山田玲司)  made comments about characters with Asperger syndrome  in anime and manga.
Asperger syndrome is an autism spectrum disorder  present in about one percent of the Japanese population . Yamada Reiji is the creator of the non-fiction manga series Zetsubō ni Kiku Kusuri  (‘Medicine for Despair’). He says Asperger syndrome makes for the perfect protagonist for manga and anime:
…To be frank, it's only been the past twenty years or so that the trend has been to label people who are a little “different” as having a clinical diagnosis of some kind.
While I'm not sure if it's a disease or a disability–it depends on what expert you're talking to–we're now into what's called the “Asperger Hero.”
According to Yamada, people with Asperger’s syndrome make interesting protagonists because they have high degrees of rationality as well as “analytical skills and intuition”, while lacking human empathy:
Speaking very generally about the characteristics of people living with Aspergers, they have some super abilities, such as: high degree of rationality, analytical skills, logic and intuition. You could say they have “high specs.”
However, people with Aspergers lack empathy. It's because they live in their own world, and with a high aesthetic sensibility, which leads them to rub others up the wrong way.
“Asperger heroes” as dramatic trope
What Yamada calls “Asperger heroes”–characters whose intelligence makes them admired, but never really liked–are regular fixtures in Japanese manga and anime. According to the trope, the hero’s lack of empathy is tolerated because he (it is most often a young male) has a some sort of “super ability.” One well-known example is the character ‘L ’ from Death Note , a police detective who doggedly and expertly pursues a serial killer known only as ‘Kira ’. Sporting ill-kept black hair, L is perhaps an Asperger hero par excellence. His lack of social grace is tolerated because he is good at his job.
The dramatic trope of the “person with Aspergers as hero” is not limited to Japan. According to Yamada, the BBC drama Sherlock  starring Benedict Cumberbatch, with Martin Freeman as his sidekick Watson, is a representative example of this character-type:
For example, there's the detective Sherlock Holmes, who has been been resurrected in the popular contemporary television series on the BBC… Asperger syndrome lends itself to “buddy dramas.” There's a cool character doing all this stuff and, standing next to him is a representative “normal” person. “Sherlock” is a perfect example of this.
Using “Aspie” as slang in Japan
The title of the Niconico article in which Yamada's interview appears is “Considering Why We Love Protagonists Who Are ‘Aspies’ Or Have Developmental Disorders” (Asupe Ya Hattatsu Shogai No Shujinko Ga Ai Sareru Riyu Wo Kangaete Mita, アスペや発達障害の主人公が愛される理由を考えてみた ).
The Niconico article uses a Japanese slang term for Aspergers, asupe, which roughly translates into English as “aspie “, meaning someone who displays the characteristics of Asperger syndrome. Yamada uses the more clinical Japanese term “Asper syndrome” (アスペルガー症候群).
In Japan the term “asupe” (アスペ ) is recognised as a playful insult and is often broadened to include people who behave differently from the majority, or act “weirdly”.
For example, one Twitter user uses asupe to make a derogatory remark about AKB48 teen music group member Ozono Momoko:
顔面から滲み出るアスペ臭 pic.twitter.com/p1gfp6nKst 
— ぼぶ田ぼぶ子 (@RIKACHAN_SUCHI) May 3, 2017 
Her face just reeks of asupe.
This Internet trend in Japan was recently noticed by the Korea Times :
Japanese netizens in their 20s to 30s are using the term “asupe” to refer to a mentally disabled person or “those who behave differently from the majority.”
The Korea Times article quotes from a Japanese-language column by Japanese psychiatrist Hoshino Geinan.
Writing in the Japan-based weekly magazine Bunshun  in late April, Hoshino wrote about the use of the term asupe, seemingly in response to Yamada:
Simply put, you should never say “you're an asupe” to anyone. This is because, even clinicians with specialist training in psychology must be absolutely certain themselves before making a diagnosis of Asperger syndrome. Since it's so difficult to diagnose the condition, simply stating someone is asupe would be a misdiagnosis.
Hoshino also wrote critically of the term's use in insulting contexts:
Will (people living with Aspergers syndrome) be happy to hear the term asupe used as slang, I wonder? Even if “you're a total asupe” is said in lighthearted jest to someone who may have been diagnosed Asperger syndrome, it may be shocking to others listening in.