The Great Train Operation - S1.E24

The princess of Sou Beil, Matilda, comes to visit the capital of Roxche and Treize in secret by traveling on a reserved train with Travas' team as her guard. Allison and Lillia get on another train for a sightseeing trip (though Allison really did it to see Travas again) and on the trip their train breaks down. The train with Matilda and Treize stops next to the broken down train, and after some talk, everyone from the broken down train are able to board the working one. As Treize and Lillia separately go for tea, they meet each other half way and Lillia demands to know why he is on this train.