400? You mean 40, surely. 400 words a day is impossible. 40 is a stretch. One might with heroic effort be able to LOOK at 400 words a day, but to actually remember them? No way. And even if you could “remember” 400 words a day, which you can’t, you still wouldn’t understand 90% of what was said to you by a Japanese speaker. You’d be just hearing gibberish. Sorry if I perhaps misunderstand your post.
400 words a day. lol. Imagine having the nerve to claim something so sbsurd.