Well, I don't know Tokyo, so can't name an exact place.
But I'd take him to a place related to knowledge. Maybe some planetarium, where he could see the moon, planets and stuff, or to an art museum, or to some filarmonic orchestra presentation - music wasn't a commonality, even between nobles in Feudal Era.
I saw many times authors approaching the topic of "Sesshoumaru learns about future" focusing in aspects like pollution, wars, crime - but I think there's more to it. Well, sure, mankind still fight and hate and destroy - we're humans, after all. But in the last 500 years we still made advances in many wonderful fields, like arts and science.
So, you know, instead of taking the demon to the cliché trip to the nearest mall... Take him to some place with meaning.