One day, while on a delivery to a certain mansion, Lag is asked by Ray Attlee the owner of the mansion, to search for the person who sent a picture-letter to her. Ray says that the pictures in the letters reminded her of her hometown, and gave her the will to continue to live on and fight her illness. Lag, after being called a "Letter Specialist" by Ray, decides not to rely on his shindan that allows him to see the heart contained in letters, and does his best to search for the sender. He discovers that the paints used to paint the letters have some connection to Ray's hometown, and then...

Lag visits the town of Blue Notes Blues, steeped in the legend of the Maka, the mysterious creature deeply connected to Niche. The people in town witnessed someone like Noir heading into a cave, however the Mayor, Khari Tonov, tells them that cave is where the Maka lives and is dangerous, and entry is forbidden no matter who it may be. But despite this, at Niche's suggestion, Lag heads toward the cave wanting to find out more about what Noir was up to.