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.
and then mathematicians around 
the world spent 150 years
ثمّ قضى علماء الرياضيّات حول العالم 150 سنة
die Mathematiker schon seit 150 Jahren
zu beweisen versucht hatten.
Depuis 150 ans,
les mathématiciens du monde entier