cant find save file yet but there is plenty of simple guides like this one : http://dldou.com/archives/24476
and after you got all character endings just start the game again and there will be bonus scene.
Re: [New Release][140912][softhouse-seal] セックス あ~ん♪ パンツァー パッケージ版 [735M]
If you don't want to click a lot , just click the title name on the main menu, all stuff will be unlocked.......