Nasa and Tsukasa take an overnight bus to visit his parents in Nara. They attempt to enjoy the trip like a honeymoon, when Chitose shows up at a service area, asking to know why Tsukasa married Nasa, who happens to overhear the conversation and begins to wonder the same thing. As the couple attempt to enjoy seeing the sights in Kyoto, Chitose appears again. She attempts to test Nasa to see if he's worthy to be married to Tsukasa, and he explains why he decided to marry her.
There's this thing called 
the Drake equation...
...هنالك ما يسمّى بمعادلة دريك
Es gibt eine leicht hirnrissige Formel,
die man die Drake-Gleichung nennt.
Es la ecuación de Drake,
una fórmula que parece una locura.
Es la ecuación de Drake,
una fórmula que parece una locura.
En mathématiques, il y a une proposition
qu’on appelle l’équation de Drake.
La chiamano l'equazione di Drake...
Chamam de equação de Drake...
Есть уравнение Дрейка.