lesson 5 in imabi is a lot better on my brain than lesson 4. :) lesson 5 is on nouns and pronouns (1st, 2nd and 3rd person) broken down according to level of politeness. eg. 1st person I=watashi(respectful), wagahai(polite and old fashioned), atashi(polite for women) boku(plain for men), ore(vulgar for men). there were many other words used to say i that i did not know. also plenty of words to say you and he, she or it. imabi broke this down nicely. it also goes into pluralization, speaking about oneself.
why i also like imabi is it really gives good reading practice with kana and even kanji(if u're a fancy big shot that can read kanji~~which means i hate u :( ) there is very lil romaji used in the lessons after lesson 2. it gives 1 sentence with kanji, 1 sentence with kana and the english translations. and lots of vocabulary to pick up. there are revision excercises at the end of each lesson too.