Yes, your friends are right, traveling from Osaka to Tokyo is expensive. I am writing this entry because I could only find information on how to travel from Tokyo to Osaka and not the other way round. Also, I had so many different information from so many places and I got confused until I actually experienced it myself. So, here is EVERYTHING you need to know. 


1) USE THE SHINKANSEN, IT TAKES ONLY 2.5 HOURS TO GET TO TOKYO
The fastest and most convenient form of transport is to use the Shinkansen. The Shinkansen is a bullet train that allows you to travel all around Japan swiftly. The line that connects Osaka and Tokyo is called the Tokaido Shinkansen that runs 3 trains; Nozomi - the fastest train, Hikari - second fastest train, Kodama - slowest train.  The Nozomi train takes 2.5 hours to get to Tokyo. More info on the two other trains here

*I did not take the flight because it will be much more expensive and time consuming if you travel last minute.



2) YOU DEPART FROM SHIN-OSAKA STATION
From town, you will need to take the subway to Shin-Osaka station and travel to Tokyo Station.

3) YOU CAN PURCHASE YOUR TICKETS ON THE DAY YOU TRAVEL
.. at the counters at Shin-Osaka station. There will be people around the train station to explain in english and they accept credit card for payment at the counters, so you can save your cash for the rest of your trip.


4) THE PRICE IS 14,250 YEN FOR RESERVED SEAT AND 13,620 YEN FOR UNRESERVED SEAT.
I chose the reserved seat mainly because I have a problem with sitting with strangers so if you're okay with that, you can simply pick the unreserved seat. If you are worried about whether or not the trains are crowded, no it's not - they have trains every 10 mins leaving to Tokyo. Hence, you will also need to be super on time because they WILL leave without you. 

If you are traveling from Tokyo to Osaka, it's the exact same thing, just reverse it.