The true ending of this game is when you have 20% of each Planeptune, Lastation, Leanbox, Lowee. As you will notice there is another know as "Other" this don't need to be at 20% I can be 0% to get shares on each thing you need to do certain quests which move the shares from one place to another you can find these at the "Guild" or the "Colosseum" which you get from a plan once there is 20% or more on everything but "Other" finish the game.
Here is a list of Quests and Colosseum battle you can do just ctrl+f type "Quest":
http://www.gamefaqs.com/vita/708361-hyperdimension-neptunia-...