Do you know Toden-Arakawa line? it is small, cute train. When I was in Waseda University, I escaped lecture and enjoyed tiny trip sometimes. You can go to cute nad the smallest amusement park which is called Arakawa Yuenchi. ^[1].

I think some of you may already know but you can reserve a whole train car in this line. It costs 13,820 yen for 50mins. You can choose a train car in garage, you can have party on train, you can do wedding on train, you can hold a concert on train!
For more information, please see here ^[2].