learning japanese in 20 years...realistic?

hi,
i need to learn japanese as quickly as possible. do you think its possible to master the 80000 chinese characters in 20 years? how long did it take you to master those?

You can get by in virtually any situation if you know the 2000 kanji. Some learners learn them all in a few years and others never reach that level.

As for native speakers, most adults know all the 2000 kanji they learn in Japanese class and at least recognize a few more hundreds used in common phrases, famous figures, major places and so on. Beyond this level, the kanji they know differs greatly from person to person.

For example, math or physics students are probably familiar with 冪, which means involution, but others may not recognize it. When you start living in Japan, neighborhoods or your Japanese friends may use some rare kanji so you'll know them. I think the 3000+ for advanced topics are the collective number of this kind of kanji, and no one knows all those obscure characters unless it's his hobby or something. It's like no one knows all English words in an unabridged dictionary.