\ˈhir-(ˌ)ō ˈsin-ˌdrōm\ (noun)
1. An infrequent, but nonetheless lethal, psychological occurrence in a male character from any of a variety of
TV media, particularly those found in Japanese
anime, in which the character in question experiences a drastic and negative change in personality due to the on-comings of a female character, or in order to gain a female character's interest or attention. This sudden change in behavior can lead to a falling-out with any number of friends, peers, or companions; resignation from or disinterest in a formerly favored career
track; moodiness or downright cruelty; and, in general, the taking of sudden and drastic actions that may
work as a plot device but are otherwise completely out of line. While these alterations in a character's attitude are usually temporary, they can, on instance, ruin a character
forever. If the character in question is a "fan favorite," then his sudden change for the worse is all the more upsetting to any dedicated fan. The term originates with the character Nakano "Hiro" Hiroshi of the
anime Gravitation, and how in his romantic pursuit of the character Usami Ayaka, he turns into what many fans consider a complete and utter
douche, and takes his unrequited feelings out on his bandmates and friends.
2. When a male anime character previously assumed as
homosexual abandons all prospects of a
relationship with a male because of the influence of a nearby female, enormously disappointing the avid BL fan.
"
Wow. First Spike was a total asshole towards
Jet, then he abandoned his nakama without even thinking."
"It's because Spike wants to find Julia so badly. He must have serious
Hiro Syndrome."
