The Day of the Flicker is the 39th overall episode of Tegami Bachi
Lag is seen on a bed in the same room as "Gauche"—who is seen sleeping on another bed. Dr. Thunderland is seen in the middle helping them. Dr.Thunderland asks Lag how he is feeling, to which, Lag says he's fine. Soon, Lag asks where Aria was delivering her letter (with reference to the previous episode), to which, Dr. Thunderland replies saying that she went to the place where the Airship crashed.
Niche and Aria are then seen walking into a large chasm, and then Aria has a flashback remembering the Day of the Flicker. Through the episode, parts about the Day of the Flicker were explained, as well as about the Airship crashing, which only had 6 survivors.
After that, Lag is seen screaming in the examination room, as he is releasing heart and causing Dr. Thunderland to go into a panic. The Dr. fears that if it continues, Lag would lose his heart. After a while, it settles down. Soon, Sylvette enters the room to check on Lag. Just as Lag calms down, Gauche wakes up. Sylvette, who is overwhelmed with happiness, hugs Gauche and Lag. Gauche smiles in nostalgia.