Yes there are lots of Japanese train assets on the DLS if you look closely, albeit some are a few years old - but still serviceable.
Not so much in the way of routes, unfortunately. I have pondered a couple of times trying to put together a Japanese route, as someone who extensively played the old Densha de Go and SL de Ikou console sims I know there are some fascinating prototypes out there. The sticking point is, Japanese routes do present a particular challenge to the Trainz (or any other sim for that matter) builder. Urban areas are heavily built up with structures encroaching inches from the track, wires everywhere both in terms of the OLE (catenary) and external "street" wires. Out of the city things are less intense but the obstacle with the routes I looked at is the large number of tunnels, never easy to do in Trainz, lines often running on raised infrastructure over flood plains or stations inside tunnels (Seikan and Hohuhoku immediately come to mind).
However never say never and I might take a look at something later in the year.
