anime, technology, new inventions, all that stuff
I've lived in both China AND Japan for 4 years so heres some pointers.
You want to see all the "high tech and inventions" then you better not visit Japan outside of the cities. Japanese tech is pretty low tier crap anyway but they get most of the recognition for tech because they focus it more into the entertainments market.
Things to not do while you are there: Don't flash peace signs at everyone you see. Don't do silly high pitched voices, and pray that you're not on some Japanese mans list of things to get offended by that day. The Japanese ironically are not fond of foreigners.
1. Mind your shoes when entering a home. They have places for you to store those away.
2. Be careful how you blow your nose. They take it more seriously and you can seriously offend someone.
3. You will always and forever be that "foreign guy/girl."
Also read this. Its useful and it covers some of what I'm talking about
http://www.cracked.com/article_20118_5-things-nobody-tells-you-about-living-in-japan.html