Tegami Bachi / Asada, Hiroyuki

"Lag returns from his training to find Amberground in chaos. The government is crumbling, revolution is underway, and the sun itself is going out. The Letter Bees' last chance is to penetrate Akatsuki, the mysterious capital of Amberground and source of the sun's power. But who will be the one to enter Akatsuki and forge a new world--Chico, who's prepared to make any sacrifice for her people, or Lag, who holds out the impossible hope that every life can still be saved?"--Back cover.

"Lag is reunited with his former boss, Largo Lloyd, now one of the leaders of the insurrection against the Amberground government. With Largo's help, Lag uncovers long-hidden secrets about his strange birth, the cryptic memories collected from children born on the Day of the Flicker, and the nature of Amberground itself. Meanwhile, Lag's partner Chico faces her own dark past..."--Back cover.

Lag, now a Letter Bee rookie in the perpetually dark Amberground, meets Dr. Thundercloud, Jr., a peculiar man who gives him a piece in the puzzle surrounding Gauche's disappearance.

On the way to his final interview at the National Postal Service, Lag discovers Niche, a feral young girl with surprising powers, and invites her to accompany him on his journey, which takes an unexpected turn when Lag's crossing pass is stolen.

"After years of searching, Zazie is on the trail of the Gaichuu that devoured his parents' hearts. But the hunt will force him to learn more about himself--and his past--than he ever imagined. And Emil, the kindly blind girl who runs the nearby inn, has an terrible secret"--Back cover.

The secrets of Amberground are revealed, including what the Beehive director Garrard saw in Amberground's capital, and why Largo Lloyd joined the rebel organization Reverse.

While Lag is out sick, the Beehive's second in command, Aria Link, takes over his route and must navigate the dangerous Amberground countryside with only a violin as protection. Meanwhile, Lag's illness changes strangely.

Gauche Suede, a member of the Letter Bees, a corp of messengers who risk their lives to keep the lines of communication open in the dark, giant insect-infested world of Amberground, is surprised to find his last task of the day is to deliver Lag Seeing, a young boy whose mother has been abducted, to his aunt, on a dangerous journey that inspires Lag to become a Letter Bee.