The Hydrangea-colored Picture Letter is the 19th overall chapter of Tegami Bachi Manga
Lag and Niche begin their journey to the mansion. Upon arriving, they are greeted by a tall woman named, Kimidori. Then, an older woman named Colbasso asks if the Letter Bee has arrived. Lag is invited to speak to their master.
The two of them search all around town, unable to find the artist. They come back to the mansion, only to see a woman in the hydrangea garden tending to the flowers with dirty fingers. Lag immediately blames her, to which, she agrees he is correct. She then asks Lag not to admit it to Master Rei. Lag promises not to, but didn't know Colbasso was spying.
Before Lag made it back to Rei, Colbasso had confessed she was the one to draw the photos to Rei, to which, angered Lag, because he knew Colbasso faked the story and that Kimidori was the artist actually. Lag realizes that he cannot reveal to Rei that it was Kimidori, but nothing is stopping him from "shooting them."