Pigeo Nation's Institute, an elite school for birds—as she finds love among her avian acquaintances.Bad Boys Love, a hidden alternate story mode, opens with the discovery of the protagonist's corpse, after which the player follows her best friend Ryouta Kawara as he investigates the circumstances of her death and unravels darker conspiracies surrounding the school.There are thirteen (fourteen in the 2014 remake) endings in total: one ending for each of the main love interests, three extended endings for three of the love interests based on stat values, one ending for the gaiden-esque Torimi Café storyline, and one ending attained if the player fails to romance any character.When routes are completed, documents are unlocked that provide insights into the game's overarching storyline.On weekdays, the player can also choose which classes to attend, which changes one of the protagonist's three stats depending on the activity chosen.Having certain stat values are required to obtain the good endings for each love interest and to otherwise advance along certain routes.In the 2014 remake however, the option to save is available at all times, the skip function is retained, and text is no longer highlighted.
In Bad Boys Love, it is revealed that Hatoful is set in a post-apocalyptic, dystopian future—in which a pandemic of a deadly, mutated strain of the H5N1 virus, or bird flu, nearly wipes out mankind in the year 2068.
A free demo version of Hatoful made with the Famous Writer engine was released later that year, followed by a full commercial version released on 30 October 2011 at COMITIA 98, and an English version released in February 2012.
An international remake by developer Mediatonic and publisher Devolver Digital, dubbed Hatoful Boyfriend HD in Japan, was released on 4 September 2014 for Microsoft Windows, OS X, and Linux and for Play Station 4 and Play Station Vita on 21 July 2015 in North America, and on 22 July 2015 in Europe, respectively. Hatoful Boyfriend received generally positive reception; reviewers praised the game's replay value as well as its writing and characterization, while repetitive gameplay and the accessibility of the game's Bad Boys Love mode received a more mixed response.
The release of a counter-virus, cultivated to destroy the virus' avian carriers in a desperate attempt to stop the spread of the disease, ends up backfiring as birds who resisted the counter-virus instead developed human-level intelligence.
Society has adjusted to the avian conquest, though with minor bird-related cultural changes—for example, while some holidays such as Christmas and Tanabata are celebrated much as they are in the present day, a major event in the game is Legumentine's Day, an amalgamation of the traditions of Valentine's Day and Setsubun.