Can eat/drink in train?

Are we allowed to eat or drink in Hakone Tozan Railway or buses?

It would not be good manner to eat on these trains and buses, especially not if it is crowded.

perhaps not good manners but still i see many young japanese people(and sometimes older too) eating on my local trains...

Shinkansen, airport trains (like the Narita Express or the Meitetsu uSKY), and scenic trains (like the Shinano Wideview or Hida Wideview) still generally permit eating, and offer pull-down trays for passengers.

Commuter trains, like subways or intracity JR lines, don't have seating arrangements or tables to accommodate eating, and because of the number of people riding the train, they discourage it.

In the same way, highway buses between cities will have tables for eating, but commuter buses inside a city won't have tables or seats arranged in a manner meant for people to eat or have a lot of private space.

Basically, if you are riding on the kind of bus or train that requires a seat reservation, or the bus/train ride is expected to last for more than an hour or two, tray tables will be probably be provided on the seats. And that is a good sign that eating is OK.

Commuter trains and buses generally frown on eating/drinking, and often have signs posted asking for you to not do so. That doesn't mean anyone is going to get thrown off for a sip from a PET bottle. But opening up a bentou and pulling out chopsticks is probably a bit much.