Crimson Melody is the 38th overall episode of Tegami Bachi
On the government's request, Largo Lloyd sends Zazie to be in charge of the personnel that will head east to destroy Cabernet. Lag undergoes examination by Dr. Thunderland after he fired too many shindans. Aria Link is sent to deliver a letter to Houdai Franklin, a man who worked aboard the airship.
Upon hearing this, Lag sends a reluctant Niche to accompany Aria as her temporary "dingo." The duo head for Black Cherry Pond, which leads to Houdai's current residence that is rife with gaichuu. While crossing the pond, they are attacked by Gaichuu Tequila Sunrise. Despite Aria's objections, Niche goes to attack the gaichuu, prompting Aria to use her Crimson Melody (shindan) to attack.
However, Aria loses concentration as she hasn't attacked for a long time. When the gaichuu captures Aria, Niche sees her memories of the time she grew up and later worked with her dingo, a dog named Bolt: Thanks to Bolt, she plotted a set of safe delivery routes for the rest of the Bees. Despite being disappointed that she has no worthy skill to deliver letters, Aria continues to rely on Bolt for his support. The story concludes.
Niche frees Aria from the gaichuu and encourages her to fight, saying she's the only one able to defeat them and translated Bolt's howls that he will always protect her. Aria is encouraged and finally gains the concentration to destroy the gaichuu. A flashback is seen showing Aria worried about Gauche's safety and well-being, while Bolt had to retire from his duties due to old age. Aria wanted to quit but was told by Largo to stay on as administrative assistant (submaster).
Meanwhile Lawrence is seen talking to Signal and Signales, the gatekeepers of the Bifrost Bridge, who are both revealed to be supporting Reverse. Lawrence informs Signal that Cabernet has been spotted and his people will soon direct it to attack Akatsuki.