Having slept through all four of her alarms, the energetic Narumi Momose finds herself running late for her first day of work at a new office. As she races to catch her train, she makes a promise to herself that none of her coworkers will find out about her dark secret: that she is an otaku and a fujoshi. Her plan goes instantly awry, though, when she runs into Hirotaka Nifuji, an old friend from middle school. Although she tries to keep her secret by inviting him out for drinks after work, her cover is blown when he casually asks her whether or not she will be attending the upcoming Summer Comiket. Luckily for her, the only witnesses—Hanako Koyanagi and Tarou Kabakura—are otaku as well. Later that night, the pair go out for drinks so that they can catch up after all the years apart. After Narumi complains about her previous boyfriend breaking up with her because he refused to date a fujoshi, Hirotaka suggests that she try dating a fellow otaku, specifically himself. He makes a solemn promise to always be there for her, to support her, and to help her farm for rare drops in Monster Hunter. Blown away by the proposal, Narumi agrees immediately. Thus the two otaku start dating, and their adorably awkward romance begins.

Tightly clutching his Gibson guitar, Mafuyu Satou steps out of his dark apartment to begin another day of his high school life. While taking a nap in a quiet spot on the gymnasium staircase, he has a chance encounter with fellow student Ritsuka Uenoyama, who berates him for letting his guitar's strings rust and break. Noticing Uenoyama's knowledge of the instrument, Satou pleads for him to fix it and to teach him how to play. Uenoyama eventually agrees and invites him to sit in on a jam session with his two band mates: bassist Haruki Nakayama and drummer Akihiko Kaji. Satou's voice is strikingly beautiful, filling Uenoyama with the determination to make Satou the lead singer of the band. Though reticent at first, Satou takes the offer after an emotional meeting with an old friend. With the support of his new friends, Satou must not only learn how to play guitar, but also come to terms with the mysterious circumstances that led him to be its owner.

On November 22, 2010, Japan was hit by missile strikes, a terrorist act that fortunately did not harm anyone, becoming known as Careless Monday. Quickly forgotten, society goes on about their lives as normal. During her graduation trip to America three months later, friendly college student Saki Morimi's life is forever changed when she finds herself saved from unexpected trouble by Akira Takizawa. Takizawa is cheerful, but odd in many ways—he is stark naked and suffers from amnesia, believing himself to be a terrorist. In addition, he possesses a strange cell phone loaded with 8.2 billion yen in digital cash. Despite Takizawa's suspicious traits, Saki quickly befriends the enigmatic young man. However, unbeknownst to her, this is the beginning of a thrilling death game involving money, cell phones, and the salvation of the world. Higashi no Eden chronicles Saki's struggle to unravel the mysteries behind her savior, while Takizawa himself battles other individuals armed with similar cell phones and returning memories which reveal his possible connection to the event from months ago.

For the first time since graduating high school, 30-year-old Moriko Morioka is unemployed—and she couldn't be happier. Having quit her long-standing job of over 11 years, Moriko quickly turns to online games to pass her now-plentiful free time, reinventing herself as the handsome and dashing male hero Hayashi in the MMO Fruits de Mer. With the pesky societal obligations of the real world out of the way, she blissfully dives headfirst into the realm of the game, where she promptly meets the kind and adorable healer Lily. Befriending each other almost instantly, the two become inseparable just as Moriko herself becomes more and more engrossed in her new life as Hayashi. Eventually, Moriko adopts the reclusive lifestyle in its entirety, venturing out from the safety of her apartment only when absolutely necessary. Meanwhile, unbeknownst to Moriko, a timid 28-year-old corporate worker named Yuuta Sakurai has also logged onto Fruits de Mer from the other side of town. Coincidentally bumping into each other at the convenience store one night, both write off their meeting as no more than just another awkward encounter with a stranger—however, fate has more in store for them than they think.