No doubt, you've see those photos of train station employees stuffing Tokyo commuters into crowded trains. This is something like that, but adorable.
"Norurun" is a Japanese pun: "Noru" (乗る) means "to ride", while "runrun" (ルンルン) can mean "bouncy" or "euphoric". Thus, "Norurun".
Norurun sure has some devoted fans.
Of course, these folks are just screwing around!
There are lots (I mean, lots) of local mascots in Japan and many of them are also rather large. But, you don't typically see them trying to do normal crap, like going through a ticket wicket or boarding a train.
Daily life is so tricky:
Doorways are difficult:
You know, Tokyu could always rename the character "Nofitfit".