The company helps a lot for an easy transition into both teaching and into living in Japan. You're still expected to demonstrate a reasonable level of independence and good sense, but they can carry you through the rest. You should still take the initiative to research and understand what experiences you want to have during your time in the country. They give you a job so that you can support your own lifestyle in Japan, but you have to decide exactly what you want that lifestyle to be. In that case you should be fine.